If you used those mailing lists often enough you had a kill file so you could filter out those who were intentionally disruptive.
I think the negative contribution from Github is the "gamification" of development. Stars, in particular, are emblematic of this problem, as it grants a measure of "apparent quality" yet it's not safeguarded in any way at all so now it just measures "apparent popularity."
The mechanisms you have to employ to be popular are almost diametrically opposed to those you have to do to write quality code.
