This is what is breaking down I feel. And what we're seeing is just a symptom - employers want to ban workplace politics not because politics and participation is bad per se, but because it has become so dirty and vicious that allowing it can literally destroy the company. You can't efficiently work together with people you hate, and I definitely feel like hate has become the primary weapon and the primary drive of US politics. It is basically required from anybody who plays in it to hate your opponent, and to hate everybody who doesn't march in lockstep with you. If you don't, you're probably secretly in league with "them" and must be targeted for hate yourself. There's no respectful disagreement, there's no difference of opinion allowed, there's no assumption of good will and willing to work through disagreements. The slogan of the day is "burn it all down". Of course there's only two ways for the company to survive in such environment - either everybody thinks the same and wrongthinkers are expelled - thus ensuring all hate is directed outside the company - or ban the politics and keep the hate outside the place of employment. Third way would be to actually remove the hate from the equation, but it doesn't look like there are enough grownups around for this to happen.
> I guess an other possibility would be to have proper unions
I don't see how the unions - especially US unions which are completely partisan - would help anything, except making the union shop inaccessible to those who isn't willing to join union's party.