I'm curious how things look for people who are only friends with people of their extreme political persuasion and only likes/follows similarly extreme pages? Does giving some variety of relatively less extreme viewpoints cause a reduction extreme viewpoints?

Perhaps it isn't the purview of an infrastructure company (Facebook in this case) to attempt to manipulate society?

This is certainly a desirable change from a user perspective. However, the issue under discussion is coordinated abuse by a group against some entity. I don't see how this addresses that.

only what your friends share in chronological order => bad actors can't influence what gets shown first and if a friend shares disagreeable coordinated materials unfriend

You just need to spam people then.

Heck - the original fake news phenomenon was Macedonians (?) making websites that looked like news sites to earn click through money.

People could just do that - “spam from the poisoned well”

If someone shares SPAM you will see it once and then it will be below what you check the next time. You can unfriend someone that shares too much SPAM. You can report it too. There's no good way for an adversary to game an aglo that decides what to put on your timeline more often when the algo is most recent first.

How do I keep my friends from sharing means. There are a lot of them.

unfriend them

That loses the good of being their friend with the bad. On facebook I only have people I know personally, and so I want to see their family pictures.