It gives people some comfort and motivation, same as religions do. I’m not saying everything that lasted so long has scientifically verifiable benefits, but they clear have some societal or mental benefits otherwise people wouldn’t do em
This sounds like saying "Everything that human beings do is good, because if it wasn't, they wouldn't continue to do it!"
Ok, then let's put it all together and say that people are interested in whether or not yoga has concrete benefits above and beyond comfort and motivation, which, while obviously valuable, are not the stated benefits.