Tube integrateds and amps generally cost more for a given level of sound quality than comparable solid-state gear. And for a given amount of $$$ you can get more power from solid state than from tubes. If someone has a budget of say $15 to $20K for a system, they can "get more power for their money" with solid state and drive nearly any speaker out there.
But yeah, people simply love tube amps and the soundstage they can provide that few solid-state amps seem capable of so there is that.
I hope tube amps stick around for the long haul. People should always have options, nothing wrong with that.
In 20 years will people be having the same argument about Class A, AB, and D solid-state amps?
Why is solid state more popular when tubes are better?
Yes tubes are more involved and require periodic maintenance. Hybrid tube components need not apply, these are really solid state.
Tubes are better for multiple reasons and yet the world and the trade prefers solid state. Those rare audio shops that are geared toward stereo listening and serious connoisseurs tend to Focus more on tubes. Those in business who like to improve volumes tend to offer solid state. All the YouTube channels looking to improve their business tend to be solid state. Maybe because tubes require much more expertise to sell, and there's lesser and lesser to go around. Solid state is more of a fast food commodity.
Tubes are difficult for businesses due to all the maintenance and complexity so you see it less often. Much much easier to sell hybrids or solid state.