That may be the case, but a simple reversion to the mean may also be sufficient explanation. If everyone plays in a globalised (more or less) even playing field, then sooner or later they catch up and the initial lead will matter less.
They have a very different feel from cotton t-shirts, which I would normally change daily.
I was also quite skeptical when I heard, and occasionally ask others to make sure I'm not fooling myself w.r. smell. Also, if I did heavy sports in them, I may stop, even if it was just a week or two. Casual daily wearing could easily go for a month.
Cost about 30€ instead of previously used 3€ cotton T-shirts.
Can wear one for about 3 weeks without washing, with no body odor. Much more pleasant to the skin, even for doing sports, driving, etc. Also, warm in winter, airy in summer. Plan to switch most clothing to merino wool.