Sure, Mitch McConnell responded to his incentives correctly and made a shrewd strategic move in implementing a generally obstructionist strategy. But I don't think that this gets McConnell personally off the hook for doing bad things. In fact, this is exactly the sort of situation in which people who don't like obstructionist politics should do a lot of angry Mitch-blaming.
Part of the reason to have angry public criticism of people, as a social institution, is so that we can set up costs for bad behavior that we aren't punishing with enforceable rules. I may be following my incentives perfectly well in overusing scarce communal resources for my own personal ends. But if I do so it still makes sense for others to express anger towards me. Maybe their expressions of anger and the social consequences of their expressions aren't enough to shift my individual utility calculus against selfish behavior. But their anger against me isn't any less justified for that.
I don't know what held things together and prevented rampant filibuster abuse for so many decades. Certainly, it isn't holding things together anymore, so it's time to change the rules. (If "Don't blame Mitch McConnell" means "Don't think obstructionism would stop if the Senate GOP leader had been someone else" or "Focus on changing the filibuster rules rather than trying to change who leads the GOP in the Senate" those are things I definitely agree with.) But if there are any public and social costs of strategic obstructionism, they're costs McConnell should very well have to pay.