Likely because the original company had terms similar to others where digital content "ownership" is only an "ongoing license/subscription to access" which they can revoke (which is the real issue with any sort of online digital media)
Funimation bought Crunchyroll, then moved everything to the Crunchyroll name.
"Crunchyroll" isn't the one doing this...it's funimation. Which, arguably, only make it worse. If funamation wanted to it would be easy....they don't want to honour those purchases.
Edit: I just found out technically Sony is the one that bought Crunchyroll and is technically "merging" them. So again, would be 100% possible if funimation sony wanted to.
Exactly. Somewhere in the Funimation ToS, there is almost certainly a clause that absolves them of any obligation of keeping anything you bought available to you at all times. You never owned anything you bought from Funimation in the first place, so there is no obligation to fulfill for Crunchy Roll.
This shit should be hella illegal. Same with 600 page long ToS. You're buying a movie, not negotiating a global trade agreement. Companies should not be allowed to redefine words in their fine print. Whoever approved these practices should be dragged into town square, tarred, and feathered.