Bad ideas always need censorship to survive. Freedom of speech has a tendency to weed them out. Err on the side of more freedom. It usually ends up not being in error.

There are behaviors such as spamming that can be addressed through technological, algorithmic means. Most sites now have built-in features to impose quotas and rate filters. That way, people are not really restricted in their speech, they have a clear expectation if they do want to build some form of automation for posting, analytics, or aggregation, and people are not impacted in what they can see. Spam can be a way to keep people from using free speech, which comes with freedom to also receive that speech, by obscuring other content. So, there, one can make a clear argument what to restrict that is also less prone to gray zones. If you want to make more than a post every 10 seconds or so, or more than a hundred posts in five minutes, you just have to slow down. There is probably very little that could be said without such restrictions. It is a restriction that impacts computers, which are the only entities that could create posts at such a pace, more than humans.

But I am not on board with the euphemistic way the term spam has come to be used, which is to describe content people deem as lacking value. That is entirely up to the reader and can be wielded in the same cry bully fashion with which harm comparable to physical has come to be alleged online to censor. Neither are we are not mind-readers who can determine with what mindset a person has authored a post.