I think it's because it's almost never accompanied by "we may have fucked up, please help us understand how to fix it now and in the future".

It's almost always (like this time) "I'm sorry you feel that way, please spend more of your free time<EOF>", and sometimes (like this time) "[we're doing it anyway but maybe we'll make some changes]".

It feels insulting because it is insulting. The decision has been made, they just want to not feel bad about you being insulted.

Changing the medium to a private conversation also means not committing to any decision publicly for as long as possible. It feels like damage control and protecting your own image (the person posting with respect to their company) as opposed to addressing the real issue promptly and transparently.

Another reason in context of public forums is that it's dismissive of any concerns or questions raised: If a call would be sufficient, that implies they think that nobody else cares.

At some point, "quick calls" are used for discussions that they don't want a trace of.

So, even in the best "sorry we screwed up" scenario, the quick call covers their butt and let them leeway to backtrack as needed. That's also part of why we viscerally react to opaque meetings IMHO.