At the expense of mine by asking me a question, and asking me for help.

Seems rather one-sided, no? A colleague has asked for my help. Their concentration is already broken because there is a problem they need help solving, and probably their work progress is halted because they're unsure what to do about a given problem, and think I am someone who can help them.

I genuinely do not understand the objection to whipping around and offering to help that person solve a problem that prevents them from accomplishing a task, project, assignment or obligation.

I ask for help understanding the conceit here, that the person who turns around and helps their colleague is at fault of 'breaking someone's concentration' when they were asked to provide help to a coworker.

How on earth did you came to that interpretation?

The person who asks question is interrupting the other one. Asking via slack is less intrusive as it gives the colleague the chance to finish whatever the colleague is doing before answering.

Because SO many of the replies to my original inquiry seem-by verbiage-to have taken what I said as an indicator that I was the one causing the interruption, not the one responding to it.

Or, maybe I misunderstood their replies wholesale, and are in fact suggesting that responding to someone who asks for help electronically with ad hoc assistance contributes to the spiraling decline of office productivity by turning to the person sitting 36" away and offering the requested assistance.