There is blame enough for both twitter and the asinine people here who engage in the deliberately misleading communication, fraud and harassment.
Capability is not a moral license to hurt others. If it were, you'd be morally responsible to kill as many people as possible.
My third paragraph is saying this: The US elections were decided by and large by social media plays. There are hints of illegal use by campaign actors, but even beyond that it was the first election we had where widespread bots on facebook and twitter were engaging the electorate. That and the repeal of the VRA are definitely factors in why the democrats lost while still keeping the popular vote.
I've been in this industry since a time when I was a teenager being laughed at for texting ("It'll never catch on."), using social networks ("Why not just call them?"), and reading online news ("WIRED doesn't put real journalism on their website, and slashdot isn't news"). Many people who are on the internet today take for granted that society has accepted this state of affairs, but it's the work of decades of amassing respectability and providing value.
And now in the public eye: dismantling the ability to associate and speak freely because the majority of even first world rich actors cannot use it responsibly.
Sure, there is blame for Twitter and Facebook for not ignoring the problem. But the people here relating in a chipper tone how they're undermining the system because, "Tragedy of the commons?" They're so stupid they're literally biting the hand that feeds them because it's a rush to commit minor fraud.
(Aside: It's very sad that Twitter fired blake so long ago, because he predicted exactly this would happen. Twitter's management didn't want to think about it, so they made him leave. Typical execs.)