Things FA has done that are worse than Weasyl's thumbnail issues:

Furaffinity has(had?) an actual rapist as the lead coder.

Dragoneer protected known dog molesters and let them stay on staff.

Dragoneer sold FA to IMVU without telling anyone for 2-3 months after the fact.

Furaffinity has archaic, shitty coding that has been exploited multiple times in the past. They never did much to fix it because Dragoneer refused to hire any professional, competent coders.

And this is just what I can remember off the top of my head.

Thumbnail issues (which I'm sure Weasyl mods will fix before too long) are pretty minor compared to that shit but idk your mileage and priorities may vary.

Also, you might not want to jump on people's journals and whine about the thumbnails, it's kind of a social faux pas and genrally not appreciated.