The shareholder system of control foists massive negative externalities on the public while concentrating profits in the hands of a few.
It's like advertising toxic waste disposal for $100 a tonne, then dumping the carcinogenic sludge in the town square while keeping the cash for yourself.
If you're a real capitalist, you peel off 1% of your windfall to support politicians who sabotage any attempt at regulating toxic waste disposal.
Is it possible that this "every FB engineer is a moral criminal" stance is actually a fringe view espoused by a radical minority and not a principle we should consider seriously? I think so. I reject the OP's claim to moral authority.
A thing isn't bad just because some random commentator on HN says it's bad. The law is how we encode legitimate and society-wide consensus on what's bad. I am under an obligation to follow the law. I am under no obligation to behave according to what some random HN commentator wants to ban this week.
So making guns is okay, supplying them randomly is illegal at most places because they just do harm.
Similarly there at these companies the engineers working to maintain the infra making it all possible.
Engineers need to understand where their work is getting put at.
Governments are trying to control it. Sri Lanka recently disabled all Facebook properties at the ISP level after Facebook promised to clean up incitements to violence but then either wouldn't or couldn't.
Just because a thing is legal doesn't make it moral or ethical. And a big reason why bad things remain legal is because bad things tend to shit cash.
I suppose you're free to do anything that doesn't get you arrested. The rest of us try to live to a somewhat higher standard.