after you sign up to reddit, it will ask you to pick a few things you like from a tag cloud. it will then try and show you more of that.

also, reddit apps that were able to block/filter subs, were able to really remove that from feeds. in lemmy, that only seems to work per instance. fir example, if someone wants to see all posts, except from memes, they’d have to block memes@xyz.net, memes@yomomasinstance.org, etc… There will probably be a new instance every day and they will therefore never be able to actually block “memes”