I have noticed this is occuring more and more. It is a problem that started to crop up on reddit but now I’m seeing here more often. Do you not want other people to benefit from the answers you received? This community is kind of pointless if you just get an answer and wipe it from the web.
Before I switch to running pifed I noticed that lemmy would still show posts, at least to me as an admin, that where removed elsewhere. It’s not a problem unique to federated things, nothing says anything you delete on a central platform is actually gone either, but federated systems are even more impossible to properly remove things from since any given node could store copies.
So yeah, throwaway accounts if you don’t want it associated is the way to go.