That only works until someone with a sufficiently large follower base promotes it on instagram. Instant tourist influx. Many of the tourist traps started out as hidden treasures.
Sure, someone might promote precisely the completely ordinary place you have selected and cause it to be overrun, but given the number of places you can choose from, that's not very likely.
Of course that only works if you don't travel to see unique and famous sights, but in that case you can never avoid other tourists anyway. If you just want some new experiences, the selection is effectively unlimited.
btw, the Taj Mahal is indeed beautiful, but it's a very small oasis in the literally the most vile city(Agra) I've been to in all my travels. Absolute filth. The best thing to do is drive there, see it for an hour, and then drive back to the place you came from.
Or go really off the beaten & easy path.
I just spent a year traveling North to South in West Africa, I can count the number of tourists I saw on two hands. It is breathtaking and well worth the visit, but it's also very difficult and demanding.
I love travel, but no, "tourism" isn't automatically the same thing.
Modern "mass tourism", in particular, consists of taking a big boat or a big bus with a bunch of people who are just like you, to places that local people never go. Then you take a picture, post it somewhere to show off to your friends, then you buy some trinkets and go to the next place.
Setting aside the question of whether or not international travel is sustainable for (say) all of China, this form of travel is ludicrous. You might as well stay home, look at pictures on Instagram, go to a buffet and and visit the mall.