In the worst case of these bb90’s, (high mileage, heavy rider), I’ve had to use Trek’s slightly OS bearings AND use JB Weld to arrive at a truly solid fit.

And I was the one who got to replace said bonded-in bearings a few years later, using a drift and “bfh” to remove the worn bearings.
It’s still going strong some additional years later under yet another (and fortunately lighter) owner.

I do make a point of allowing JB Weld to cure for a full 36 hours based on my experience with it.

Normally, bb90 isn’t such a big deal other than having to keep the proper grade of retaining compound and primer/accelerator handy.
And Trek’s OS bearings alone usually are good for at least a few extra years of service.
So part of the problem might just be that Trek’s paint and clear coat holds up well enough for people to want to keep these old bikes around for a long time.