That's technically true, but that's because nobody today really thinks about Reddit AMAs, because there are fairly few of them and they're mostly lousy.
When they employed Victoria, AMAs were frequent and involved high-profile public figures engaging with the users in a way that, even if it was self-promotion, felt relatively genuine and was entertaining - This was because Victoria was essentially interviewing people with user-submitted questions, and she was good at it. The Reddit AMA was a cultural touchstone, like the late-night talk-show circuit.
Victoria herself was not somehow utterly irreplaceable, but as far as I can tell, they fired her and replaced her with nothing. With the result that Reddit lost a popular, interesting feature and a lot of cultural relevance.
I think it's very appropriate to compare that situation with the situation today, though perhaps not as you intended it; it won't burn down the site, Reddit will go on, but it will be a little worse and a little closer to that tipping point because of yet another bad management decision.
