> evolved for millions of years for this exact type of communication
A great many people identify themselves as introverts or antisocial, and would feel much better being excluded from all these neuron triggers.
> The information bandwidth of in-person communication is absolutely unparalleled
Yes, but that bandwidth is not all used productively but wasted on irrelevant bits which do not matter and likely distract from the topic. Implying that more bandwidth helps is suggesting that a book can only be a tiny bit as effective as a video...
> Good luck replicating body language, eye contacts, subtle facial cues etc with Slack messages.
I wouldn't try. Such things are usually unnecessary to the task at hand, and often detrimental. I'm not going to replicate the odor of what my co-workers ate for lunch either, nor other clues about their general hygiene, nor would I want to even if it was easy to do.