Remember most hosting providers make a living from customers, and generally don’t pull things down unless it’s super sketchy under their local laws. Dreamhost, Tucows etc. had a reputation for years for being very liberal with their hosting. Pretty much anything goes that’s not blatantly illegal.
And for the many sites with controversy, they probably don’t use a hosting provider.
People used to run entire forums like HN (smaller scale) on their college dorm PC; this is how Slashdot started. It’s not that hard if a college sophomore can do it. As you scale, you probably move to an actual house or building and need more servers and get a leased line from an ISP.
Yes people can appeal to the internet provider(s) but they rarely act. Remember, Stormfront was self hosted for ~25 years and only got torn down because of Charlottesville. Turns out if you actually do things (rather than just talk) with shitty ideas, at least in the USA, this crosses a line.
It's not a slippery slope, it's not harder to run your own website. Don't extrapolate from a few extremist cases.
...and if you are find out what hosting services they use and use one of them.