The downside of using external sites to post photos is that if the link is broken, the photos are gone. I find it such a shame to go through threads from several years ago and the photos are gone....
The website significantly downsizes images, because it hasn't been update in years and the size it uses no longer reflects the storage size of modern day servers.
I still remember the early years of the forum where it was frowned upon to imbed full sized images via flickr or similar, because folks on dial up modems had trouble getting the page to charge correctly!!