I think my contributions are being deleted/removed

My memory of contributions is rather hazy, but I can recall having updated some anime shows/voice actors with miscellaneous sites (Anime News Planet, Anime Planet, My Anime List, Anime Screencaps, etc), and then coming back to them later and finding those sites removed. 

IMDb has freedom for users to do what they wish, and there is no rule that forbids changes to links, but this feels like nitpicking, at best, and at worst trolling. The frustration of having to put back those links again, and to possibly have to do this again in the future, is a terrible feeling. And I can't think of a solution for this problem either.