Nothing wrong with a friendly face, its more that it can throw you out of your flow, especially when trying to debug some code. This describes it best:

https://heeris.id.au/trinkets/ProgrammerInterrupted.png

This for me is why WFH suits me so well. In my morning I get around 4 hours of pure uninterrupted coding (as long as I stay off here or reddit).

Some of us are more likely to worry about work not getting done than others. When those same people also have less general need for social interaction, that 'friendly interruption' feels like a selfish demand to meet your greater need for social interaction at the cost of my own need for lack of worry about the thing I get paid to do.

My case is similar to BossingAround, sometimes I wonder if I have https://en.wikipedia.org/wiki/Misophonia, every little sound irritates me.

EDIT: I didn't really drive my point home. It's not the friendly face that bothers me, in fact if it was a friendly face then it would hurt me less. But it still hurts regardless.

It’s selfish on behalf of the distractor.

When using async communication the person can wait until they’re out of the flow and respond. This is one of the great things about email, and the worst thing about Slack.

Well, how about doing just the work and working less hours a day, because of fewer distractions and see your friends after or before work?

Sounds more sane that forcing an office environment, where I understand that everyone wants to socialise, but why spent more hours for work than necessary?

Because flow...