This is an interesting question that comes up from time to time and it's actually not as it seems. While it is work and taxing at all, the whole act of explaining is actually not very expensive. In fact, it is simply tapping into the stream of consciousness and piping it into a text input.
What _would_ be expensive actions would be to:
a) _not_ explain, see that something isn't quite right and then try to handle the internal discomfort sparking from that.
b) mask and play a different "more polite" role, which actually just means "accepting the unsolicited emotional offloading and the task of handling those attached to it"
both being "providing a service" to the random person that just approached me, and operating in a style that is unnatural to me. This is counterintuitive for the vast majority of people, because for them it works exactly the other way round.
Doing this emotional labor for free would also be just giving away the thing that makes me money. Specifically, being able to understand technical details and also communicating those to people that won't necessarily do.
Effectively, the free-plan includes technical support but not emotional consulting. This, for some, is hard to understand, for others, it is hard to accept.
And, of course, it always gets worse when social media (like HN) is involved, because these machines erase any context and replace it with violently jamming in defaults + rewarding those that dunk the hardest and make the in-group of the mob feel pleasant feelings.