[SolarNet]

I suspect they were aware of it. They didn't rely on it to block bad actors like bots or spammers or ddos-ers, they relied on it to block actors who were at some level implied to follow the social contract of how the internet works (e.g. a website focused at developers).

The actual lesson learned here I think is that certain communities don't have respect for the social contract when it benefits them. Though I suppose you are right, a team of linux users should never have expected a site ran by a venture capitalist firm to respect the social contract.