You can do that on email, irl, with real letters, etc. It hasn’t been a problem. If someone is particularly harassing you then it becomes a legal issue.

What Twitter could do is just stop promoting and spreading content people don’t like. Rather than completely ban problem users like trump, just stop showing them in trending feeds and give people the option to block the users so you don’t see them.

"What Twitter could do is just stop promoting and spreading content people don’t like."

Isn't this censorship?

Yes - a lot of people claim that shadow banning, downranking etc. are censorship. I disagree, they necessary to keep online places as civil as they are.

There's also content that is regarded by mental health experts as harmful in large quantities - downranking that is also important to not cause existential harm to people.

Neither email nor written letters are a public forum.

Not you specifically.

The free speech advocates really confuse free speech (in the global sense not just the American amendment) with saying anything

Free speech isn’t freedom to plan a drug deal or anything or illegal

There are definitely unenforced laws regarding harassment but they fall into the illegal category

Where it’s interesting is silencing say a pro Russia person or an anti vax person

This is circular. “All speech is legal because illegal speech isn’t speech”.

It's legal to use the n word in the US as far as I know, but I think harassment probably isn't ('spamming' sounds like harassment), that's where the balancing act is. Now, it is not legal to throw the n word at someone in most European countries. Hence why I said that these platforms need to filter on a per country basis for all countries they want to operate in.

As I said, Twitter and other major platforms have become de facto utilities and it's no longer a valid argument to claim that as private businesses they are free to do as they please because they yield too much power.

It's not a "utility". It's a social media site that is arguably a net negative for society irrespective of what kinds of moderation policies it has.

Define a utility