The whole point of Mastodon is there's not just one server. Pick one you like; hell, Gab is built on Mastodon.
Since every server can pick which servers they want to federate with certain groups will not connect with each other. This however doesn't prevent you from having two accounts.
That whole argument seems like a badly disguised call for total surveillance.
Well, the line of cancelling someone until they literally cannot attain food has not been crossed... yet. But if say the Nazis were selling organic food to fund their activities, plenty of people would say it's wrong to sell seeds to the Nazis.
I'm not saying that I support this, just that this is what I see the "duty to cancel" arguments implying under these circumstances.
On the original point - it seems to me that the whole cancel culture is just an attempt by a vocal minority to bypass democratic system. Centuries of lawmaking have made some things legal and others not, walking very thin lines between good and bad decisions in order to maintain the balance between totalitarism and lawlessness - and suddenly a mob of random internet dwellers think they can get their way by throwing tantrums and bend the rules as they wish.
I'm annoyed at the very efficiency with which mob manages to cancel whoever does anything remotely "unacceptable" by their unwritten, "come on dude we all know that", rules... It seems like the futute is likely to be lead by loud demagogues skilled at tapping into the mob rage of the society and cleverly weaponizing it against their political enemies. Like always.
If you went to high school in the US, you probably read “The Scarlet Letter”. That’s about someone getting canceled, too.
Shame for behaviors frowned upon by your community has been with us forever. Even chimps throw bad actors out of the group.
If you choose an instance with rules that you agree to follow, you're not likely to be blocked in the first place. But if your Mastodon account is blocked on an instance, it's easy to make a new one on a different instance. There are many other instances to choose from and you can regain your social graph by following everyone again.
This is absolutely the argument.
It seems that for some people, the ability to control your own environment is not enough - they want the authority to control everyone else's environment, to make it impossible for people they disagree with to exist.
Of course, it always starts with Nazis, because Nazis are universally hated and not arguing against Nazis will get you labeled as one very quick. But in order to be able to make it impossible for one group of people to exist, you must have the ability to make it impossible for any group of people to exist. And that's power I would not trust anyone with.
Technically, this is federation working as intended, but it's not as diverse and inclusive as it advertises - on the contrary, it's more like a HOA that has a right to ban condo owners from talking to each other.
It's a nice place to be when you're not into politicking, but then so is Twitter, so it's not that big of a win. A more compelling argument for Mastodon is that it's community-funded, so it's not out to sell your eyeballs.