Correct, but how people use the web has changed over time. Content and interaction was also far less centralized. I had to dig for specific channels on IRC to find the kind of hateful discussion I can find in 5 seconds on Twitter. There was far less spam and noise in those days.

Many of us run an ad blocker in our browser. Is this not censorship of certain types of speech?

I block ads to not be tracked, subjected to malware and unwanted annoyances. I do not block ads to censor speech.

Censorship needn't be the primary motivator for it to occur.

It’s not a motivator at all and your argument is invalid. Secondly, hiding things on your own screen is not censorship, hiding things on someone else’s screen is.