SH, you are hereby nominated to author “AV Electronics for Dummies”
What a crystal explanation even for me on a first read. Betweens Charlie’s math and your explaination.
I have calmed down from a knee-jerk, What? more power isn't always better?

I do forget (early days yet) to think backwards from speaker sensitivity. And how incredible the difference is in 10 dB increments of these ratings when calculating power required. And then there’s impedance and as you point out …class of amp.
So at 91 dB 4 Ohms on FL/FR, and 91 6-Ohms center and 90dB on small satellite surrounds. 200watts per channel are not going to leave me ever hovering in grunge territory.

Also believe it or not (I don’t) I end up being quizzed by fellow shoppers when I’m out, (including a lot of men which I find incredible as I thought they were all born with AV knowledge) Asking me questions when a sales person has walked off after they hear me talking to sales. (I always preface my answers with …”I only know enough to be dangerous” and…”I really just have bits of this down, -Get some professional help!”) But I have talked to 2 guys already about what amps they’d want to look at while in stores thinking of beefing up their old receivers or looking into separates etc (Don’t want to steer anyone wrong…but I very clearly tell them I’m a neophyte)
Its too easy at my stage to spout genralalities without the slightest grasp of all variables involved and I try not to do it.