It is the unfortunate consequence of having a public platform. Some parties have a stake in seeing it fail, or want to use it selfishly at the expense of everyone else.
These can be competitors, criminals and big companies who rely on everything being under their control.
This is why good moderation is important and having something like adblock or a simple filter is a thing I do recommend. Note tho, just like any platform that doesn't pay their moderators, some lemmy spaces (and sometimes it's mods) are quite a mess.
Sometimes it's because orgs that make millions just decide to be irresponsible and hoard wealth (eg, wikipedia) and sometimes it's because it's run by volenteers (like a good chunk of lemmy, mastodon and matrix)
This is the single biggest reason I don't want my own instance. It would either be an instance of one or it would be a giant hot mess (or both). I don't have the time or energy to moderate a bunch of other people. It's enough trouble moderating myself.