I picked this as the summary; there’s more out there. As the article points out, the cathode stripping concept came from a different arena (in the Radiotron handbook, mainly referring to high wattage transmitter tubes). I learned a ton from Radiotron, BTW- highly recommended for anyone wanting to in depth in tubes).
The article claims (it’s very plausible) that Leo added it (at least in part) to keep costs down because it let him get by with cheaper electrolytics. And of course the others followed Leo. Today’s caps tend to be higher quality (so long as you buy good brands from reputable sources).
I’ve added standby switches to amps, and those I built always had them. Were I building today, I wouldn’t add one. I know lots of guitar/bass players who never bothered with standby switches. They didn’t seem to need tubes faster than anyone else.
The one place I might use a standby would be an amp pushing its limits, especially a high powered amp. That would mainly be to keep inrush current down.
All that said, I don’t see that standby can hurt anything if used as directed. It will cut energy usage a tad and help extend the life of the passives - and the tubes if they stay on during breaks, etc. vs being turned off.