This sort of agreement keeps on popping up. Again and again. The most forgiving reading of the intent of this sort of agreement is that "it is the basic function of a web browser to transfer your stuff across the internet, and it is the basic function of a website to do stuff like make thumbnails of your images and send them to people looking at your stuff, and you are cool with us doing this" but it always ends up b…
I worked at deviantArt back in the early 2010s, they notably had a user agreement that did not claim any rights more than necessary, and it was revocable by the user without jumping through hoops. So it's not necessary to do things this way, companies do it intentionally because they don't care about the rights of their users.
It sucks.