You raise an excellent point, and going over-totalitarian is just as likely to crush innovation as anything else.
However, I think taking an authoritarian stance on politics, religion and so on in the workplace, so long as it is done in a respectful manner and puts everyone on the same level, is completely appropriate.
When you are a group of ten, and that’s your entire company, you can get away with a lot. Everyone is going to know each other, maybe a little more intimately than some of them would prefer. Your CEO might also be your drinking buddy and a good wingman. That’s the nature of a small organization.
At 2K, things don’t have to be quite so intimate, you don’t have to know everyone by face and name, just get along with them well enough to do your jobs.
I’m not going to try and guess where the tipping point is, but at 99K or 400K, there isn’t a lot of difference between the organization ability you need. Everyone has their own ideas about Life, the Universe and Everything, some teams might get along better than others, but politics and religion and the like have led to actual wars between smaller masses of people. If you have 99K on your payroll, not all of them are going to like and respect each other. Not every team is going to have perfect cohesion with every other team.
You still want civility. Every one of those 99K or 400K people has their own ambitions and dreams and reasons for getting out of bed at whatever time of day they crawl out of bed. But there is a time and a place for it, a whole wide world and life outside that of your employer’s little world, where not everyone is necessarily on the same payroll.
Absolutely if you can build an internal social network for your workers, that’s great! If they want to debate politics outside of work, that’s great too! It is still entirely appropriate to moderate that network, and draw a few hard lines where you think it is appropriate.