Disclaimer: These are just my dumb thoughts with zero scientific evidence. Consider the opinion accordingly.

I think it’s tied to how overwhelmed everyone is at all times now. Part of it is often “thanks” is said while someone is beelining out the door, so you don’t often have an opportunity to even say “you’re welcome.” Further, “no problem” is far more indicative of “actually, you didn’t inconvenience me at all by getting my help” in a society where everyone is absolutely time-starved due to overwork/underpay. It’s saying to the person saying “thank you” that “it’s okay to have minorly inconvenienced me, it was worth doing anyway.”

Because yes, I am more likely to say “no problem” at this point than “you’re welcome” because most of the time I am dispensing technical information and advice that people usually have to pay to get. That’s the other aspect of it too, we’ve normalized that you have to pay to get anything decent (service or product) and so people offering technical skills and advice outside of a payment plan is definitely viewed differently.

“You’re welcome” is valid but just doesn’t play well in a fast-paced society where everyone expects to have to pay through the nose for decent help and generally doesn’t have the time to give out those kind of favors themselves.