Adding this option to the 3 dot menu under each post in the feed would be ideal for me. I don't want to have to open a community just to block it, especially for the myriad niche fetish stuff that somehow make it into hot.

Also instance-level blocking, while not yet a Lemmy feature, could be implemented purely within wefwef as a post-filtering step using a locally stored list of instance names. This could be a killer feature to differentiate wefwef from other apps. The first app to let me block every single fansocial sports team community in one fell swoop will be my go-to forever.