But that's only certain people calling them boutique, early klien may have that tag, mainly as they are like jewels to some people and need so many custom parts.
Fats that you mention are just another steel frame, some people collect them, some give them to the recyclers.
but then some collect the Rocky Altitudes that I have and tart them up and don't ride them, some would class them as boutique. I ride them, scratch them, get the muddy, let my kids ride them. (and wife, who scuffed up an Ti Syncros post, I leave the zig zags in, next time I'll show her how a q/r works.)
My '91 can command a high price nowadays, but that thing used to go to school, do paper rounds, drop down 100ft quarries and loads of riding.
It still rides nice now and I'd still put it into daily rider mode if the Explosif wasn't there to do it.
Just ride them.
Don't worry about damaging them.
Plenty of other have museums, even then like First Flight they may get sold off split up.
Each to their own. Some collect great big effing old planes in their front lawn.