Why would you have the app and not sign up for the program?? It's no extra work, and it's not like you're avoiding being tracked. Especially with an airline.
That's a totally different game. Of course I have individual airline accounts, and of course I accumulate those points. Hell, half the time the points and website account are the same thing now.
But that's peanuts and will never add up to much because I only fly a few times a year and it's usually on different airlines. The real miles game is accumulating points from other purchases, and churning those into free travel and such. Both generating and redeeming points in those volumes is a lot of work -- I've done it and eventually decided it wasn't worth my time.
Because I just fly with whomever is cheaper/more convenient flight time. I don't fly often enough to get anything useful out of these rewards programs, and I delete the airline's app as soon as my trip is done; the cognitive overhead of creating yet-another-login and tracking these points with a half-dozen different airlines just so I might or might not get some sort of reward in five years is in no way an appealing value prop to me.
Well there's different levels to it. He went full bore and did a lot of first class travel (which is harder to get due to low availability).
If you just take a couple of hours getting familiarized with the different frequent traveler miles program and chose the right one for your travel pattern, plus make sure to get a credit card with a decent mile accumulation rate, you can already get a couple of business class long haul flights out of it.