Of course, decentralised systems like that have their own problems, and there are reasons they're not very widely used. But in principle, a technological solution (make it easier to use/run federated, decentralised alternatives) seems preferable to a social or legal one. Assuming it can be done.
I have since changed my stance after that event: platforms should deplatform everything they don't like. It's the only way people will advocate for solutions that support free speech in all its forms.
EDIT: Everyone running their own phpBB instance is looking pretty smart right now. To own your content/speech/destiny, you have to own your platform.
The columns can be published sure, but in some fringe publications that I don't have to know about.
I also don't like the idea that all people with rubbish ideas should be able to demand distribution via any popular network/publication/institution. However when someone with rubbish ideas is already known, refusing debates or stuff like that is just silly.
Also it's good to remember that free speech means you shouldn't be persecuted for your words. Not that you can't be disliked or made fun of.
Some people don't want nudity in their platforms as well, so be prepared for those sites to deplatform with extreme prejudice.
Tumblr users publishing the sexual and nude content that they do makes them what the general public would consider a fringe publication. It should be unsurprising that Verizon/Oath intend to nuke all of it.
In this situation, it's more like Verizon buying a bookshop (Yahoo) and half the basement is erotica (Tumblr).
Europe sometimes makes me chuckle; Rights of Man and of the Citizen, adopted during the French Revolution in 1789, specifically affirmed freedom of speech as an inalienable right. But hate speech is icky, so not so inalienable!
The social contract and public policy is a balance. I do not endorse hate speech, but I am vehemently against restricting speech. Undesirable speech is the cost of a free society.
The gray band here is narrow enough to see across.
"I have enjoyed this use case that is currently allowed. I dislike the fact that this use case will be going away. If it does happen, I am much less likely to use the site. I think you should reconsider your decision."
Tumblr, of course, is free to disregard this feedback, but I cannot see how there is anything even slightly wrong with concerned users providing it.