No, it hasn't. I'm a founder. I have investors. Nobody serious is asking these questions, for reasons that make perfect sense when you're familiar with the mechanics of venture investing and corporate governance.
I won't say nobody is asking questions at all, because "investor" is a loosey-goosey term and there are plenty of people writing small checks who call themselves investors. But those people never had leverage anyway. Investors get preferred shares with no voting rights (or even information rights!). The only ones who have any power are round leads, whose board seats are enshrined in the company's articles of incorporation.
If -- and again, it's a big if -- Matt, after raising a billion dollars across many funding rounds, still controls a majority of the voting shares and board seats, it's because Automattic was already so successful that he's been able to dictate terms every step of the way. This is stupendously rare. It's not a situation that applies to other startups, or that investors are measurably worried about.