Can a power amp have too much power, risking damage to a speaker?

It really can. I've damaged my speakers with large power!

I’ve always had power amps that far exceeded the power handling capacity of my speakers. Never damaged a speakers. Particularly with solid state amps most speakers benefit from having large excess capacity, yielding more solidity.

As my systems got better the volume of maximum enjoyment went down, until now 65db to 75db is typical… cracking 80 if I am enjoying it really loud..

....nothing like the fragrance of fused voice coils to flip enthusiasm into ennui...

Note that any tube guitar amp from a 5 watt studio amp to a 100 watt whatever will often be used overdriven with distortion into the speakers for DECADES with no harm done. If people are lame enough to drive their delicate little home stereo speakers to the edge with a high powered amp (especially a solid state one) there's little to be done for them.

As pointed out in one of the threads, when the maximum power of an amp is reached, the distortion rises very quickly. It is a "bell" curve rise. The distortion goes from "zero to a hundred" really fast (smallest movement of the volume control), and the distortion created plays havoc with the tweeter/s and midrange speakers.

Not so much with a group like this, but what I saw with the "how loud will it go" crowd was, they "cracked it" and after a while the tweeter went. Five to ten percent of the sound was lost, so they "cranked it" again.  A short time later there was less sound again because the mids were fried.

Woofers pretty much have to be abused with brute over powering or "bottoming" them out with excessive bass and power. I had knuckle heads complain that their speakers were  making a "whip cracking" sound, or a "blatty" sound. As it turns out, they have the loudness button in, bass control cranked to the max, and  the volume control at 3:00 (because that's only 3/4's of the way up, it should be able to do that).

In my experience, less than 5% of the time did speaker repairs result in a woofer failing.

To go along with that, I saw more blown speakers caused by them being under powered, than over powered, and that goes back to how the distortion increases when full volume is reached..

As for the guitar amp being over driven, in most cases you are dealing with a speaker that is basically a woofer. The distortions being generated by the "stomp boxes" are in the mid and upper range frequencies. This is not really taxing or putting the speaker in any danger.