Part of the problem is that no, we do not know what they are referring to. Lots of murky lines, lots of people with bad experiences that what for them is essential is considered over lines, worry that it'll be used to silence internal discussion of things the company does, ... (and of course if you impose it on a company used to something different, it's potentially a massive culture shift)
The "you can take it to private channels" can play out either way I guess: it can be a completely valid replacement of using company channels, but it is an additional hurdle if you have no signals to go by who to talk to. And if you actually have a problem with work channels getting out of hand, I feel like it's a gamble to hope it works better in the dark.
If my employer told us we had to move the more social/less technical chat channels outside of company infrastructure, I'm not sure that'd be better overall. And sort of odd to go with each new hire "oh and btw there's this second chat without the bosses, come join".
Blacklist/whitelist, main vs master, is there a bias in promoting women, what are the rules for dating a colleague, is an anti-bias training needed are all topics that are divisive, though some of them are easy to solve (David has strong opinions for naming variables, remote working solves the dating problem and no peer reviews means that less talk needs to be done about promotions).
May I ask your basis for saying these are the issues at hand at Basecamp? Are you a current or former employee? Heard these things firsthand or secondhand?
Okay, come up with a company policy for those (and if people feel strongly about it you probably want to know rather than have them just bitch in private about it), and if people get obnoxious about it do something about that. Instead of leaving your gay employee wondering if she needs to ask permission to mention getting married because that would be bringing up a "societal or political topic" (or to pick an example from elsewhere in the thread, if someone can mention that they went on a hunting trip on the weekend).
These kind of blanket no politics policies are typically direct responses to obnoxious behavior. I don't think we know the story at Basecamp yet, but when it happened at Coinbase, it was in response to a vocal segment of employees who demanded that the company publicly recite the slogan of a political movement they supported.
The "you can take it to private channels" can play out either way I guess: it can be a completely valid replacement of using company channels, but it is an additional hurdle if you have no signals to go by who to talk to. And if you actually have a problem with work channels getting out of hand, I feel like it's a gamble to hope it works better in the dark.
If my employer told us we had to move the more social/less technical chat channels outside of company infrastructure, I'm not sure that'd be better overall. And sort of odd to go with each new hire "oh and btw there's this second chat without the bosses, come join".