At least on a standard forum, you can say "hello" and "thank you".
Hence the Q&A format was born with upvoting the best answer to the top and deemphasizing the back-and-forth into comments. It got popular exactly because it cut through all the niceties and fluff and allowed you to get to the point quick. Some people don't share the preference for this, they would like a social community site instead of the above description. Instead of building their own site with that in mind, they want to bend SO away from its original goal.
Predictably, the original people will probably move to a new site. It's a cycle: power users create a place, it gets popular because it's high quality, then it gets run over by lazy people and rules get adjusted to be welcoming and inclusive, the original people are pushed out, the quality decreases. When the originals create a new site, they will now try to be even less inclusive than the first time to avoid the same "eternal September" effect.
i) We don't have to dehumanise interaction to present clean information.
ii) I believe there is much more human motivation potential to be found in "personal connection" than there is in fake karma. I want to be thanked, I want to know how I mattered, I want to know what the user was building just as much as I want to be gracious and share how much they helped me.
iii) They are trying to use the same rules for wildly different situations. There are two faces to SO: very high traffic questions better directed to maintained documentation/tutorials, and a very long tail of 1:1 interactions that get less than 100 views and no votes. Right now SO doesn't serve either very well: the high traffic do not benefit from 10 years of highly voted bad answers and the low traffic do not benefit from the interventions of jack-booted deletionists.
iv) IMHO you often get a better experience and treated with more respect in a discussion on a GitHub issue. We don't have to turn github issues into a highly constrained impersonal experience to be effective.
The early adopters of Stack Overflow saw it as something closer to Wikipedia. A source of technical documentation. This still exists in the closest thing to a mission statement that one can find: https://stackoverflow.com/tour
> This site is all about getting answers. It's not a discussion forum. There's no chit-chat.
One similarly doesn't see "hello" or "thank you" in encyclopedias or technical documentation.
There are places for human interaction (chat in particular) - but in a question, answer, or comments it isn't useful.
Consider that the summary part of a question that shows up shows the first line or so of the text.
> Hello. I am a new user with Java but I know C#. I have searched everywhere but I cannot ...
Compared to:
> When using Java, I am trying to use a stream to select some data and write it out as a file ...
For comments, this has been looked at in the past - https://meta.stackexchange.com/questions/204402/hide-trivial... and https://meta.stackexchange.com/questions/210265/how-can-we-m...
Having comments - especially trivial comments - means that voting doesn't happen as much and that then impacts the ability to get a signal to curate on.
