I think the issue that I see with a statement like this is that it completely misrepresents the great strides that molecular biology has made and the increasing level of sophistication and diverse ways that are employed to help understand our natural world better. Some of the reorganizations and changes that have occurred in plant systematics and taxonomy are not "just" about DNA or the orchids themselves they are taking into account how these organisms fit into and enhance our whole understanding of plant evolution, ecology, geology, climate and the interplay between these large concepts. Sometime in the 90s as molecular biology techniques became available we had another tool we could overlay and help us understand "species" which is a debate in that of itself, especially with plants but again, misrepresented here.

In many cases hybrid swarms actually INCREASE our understanding of plants, not decrease. They represent very closely related forms and there can be a lot of different implications based on the study of natural hybrid swarms. To an ecologist this can be an important area of study and the underlying molecular data (molecular clocks, sequencing) can tell us important ecological relationships, past climate and even geological changes. This is a poor argument to criticize taxonomic changes.

It's also a bit of a red herring to point to a group of orchids that is poorly understood, and largely poorly represented in many hobbyists collections like Sobralias. The same can be said about Mediterranean terrestrials. I think we all know why these sections in the extremely diverse family that is Orchidaceae aren't sorted out- it just hasn't had the attention and resources put to it. Again, another poor argument. Cattleya, Vanda and Phaleanopsis are genus that have a lot more research behind them.

For example the changes to Cattleya actually make a lot of sense. They represent a genus that has significant diversity in forms and has expanded into a huge variety of ecological niches in a particular geographic area but in the end these forms readily interbreed and are less genetically distinct than we would believe if we were just using our eyes and a few basic tests to organize them. The changes were made not just by arbitrary personal opinion but by weighing multiple factors, which I have described above and certainly not in a vacuum... as if these taxonomists are just looking at a screen of single nucleotides.

If you are going to distill everything you said down to : "do we really know anything about anything" I would agree with the statement but not the implication. Its another hand waving rhetorical question that is akin to a stoned hippie asking "is reality even real?". There is no conspiracy here...there is very little money for academics in this space these people are largely helping through a labor of love to contribute the better understanding of our natural world and the labor of re-writing tags or challenging our porous memories weighs little on their minds.

If we take your position to the Nth degree, then every single plant would be a separate species.

The problem is that we are going from 18th & 19th century evaluation of measurables, to the infinite depth of analysis of DNA, and then still trying to apply human defined definitions (IE, where to draw the lines between 'genera', which are a human construct).

If we apply your point of view as to how easily the plants can breed (partially based on number of chromosomes), then we should lump broughtonia, encyclia, epidendrum, prosthechea, etc. into Cattleya also.

I have really failed to make my point if all you took from my post that the only reason for changes in Cattleya is due to the ability to interbreed. Again, believe it or not, the research sphere around Cattleya taxonomy even considered horticulturalists when they attempted to deal with taxonomic issues posed by:

Cattleya maxima and Cattleya araguansis

Brazillian Laelias

How do we deal with Sophronitis?

Ecological and geographical considerations across South and Central America

I just took one example.

Anyway, you keep missing the point that both the old and the current taxonomic distinctions are human creations (the plants don't give a damn). But, it is not something that can be codified with 100% certainty (like the periodic table).

We can keep moving the lines back and forth, but they remain rigid human constructs applied to a fluid world. There is no right or wrong in any of this, simply artificial constructs imposed on nature. As is common in such cases, some will agree, while others disagree and yet others simply ignore the debates.

Finally, while DNA represents the current level of definition, who knows what other identifiers we will discover down the road if we look even deeper into the organisms?

I think one of the problems is that it seems like the instinctual response taxonomists have when discovering one genus deeply nested in another (eg Sophronitis being nested in Cattleya) is to lump in order to maintain monophyly. But usually monophyly can also be maintained by just splitting further and make new genera, which is what I would personally prefer in many cases. For instance you can keep Sophronitis by splitting genera at the places I marked here.

I reckon erecting several new genera is probably more work for taxonomists than just lumping one genus however, so I suspect lumping is often chosen instead due to convenience.

A major point. Interpretation of any studies remains a human decision or choice. Those are always debatable.

Furthermore, we are just beginning to sequence, examine and understand DNA. Sweeping taxonomic changes have been made after studying fewer than 200 base pairs on one chromosome. I think that's somewhere between ignorance and arrogance.

I wouldn't call it arrogance. Whole genome sequencing takes a while and is really expensive, which is why researchers typically just select one or a few DNA regions to sequence.

Its not like DNA regions are chosen at random either. Many are inconvenient to study because they are hard to detect in a DNA sample or are too large, and others are just not worth studying since they barely vary between species.