I generally take a very dim view of undiagnosed electrolytic capacitor replacement. If it ain't broke , don't fix it. Usually when capacitors cause problems it is only one or a couple out of all of them that has dried up or poofed. You just replace that one and it starts working again. That is why God made service technicians.
I have been testing my late seventies gear on a good test bench lately and am AMAZED at how it all (so far about half of it) just keeps perking along and meeting really great specs. (Down in the noise of the test gear mostly). This includes three Pioneer Elite M-22 Class A Power Amp/Toasters. If anything was going to dry up these would. But this points to one of the reasons not to. Are you sure your self appointed recapping tech, knows how to pick the correct capacitors for your application. Does he guarantee a measureable and measured performance improvement?
This is a current fashion in audiophilia, that is , as usual, a method of separating money from audiophiles, who are not electronically trained nor knowledgeable. I have seen military surplus test gear from the 1930s and 40s, that still works fine, and I prefer to work on scientific gear from the 50s through late 70s because it is usually repairable.
It is correct that you can often ressurrect a dead computer motherboard by replacing the electrolytic capacitors in it and I have done this repair many times. Mostly on terminals from the 1970s that were on 24/7 and are no longer made. About 60+% came back to life with cap replacement only.
The reason you know snake oil is involved, is that they not only tell you it will start working again (if it's not working), but whether or not it is working, they tell you it will sound better. Just my not at all humble opinion. ymmv