Well, it is a local tradition, and I respect the fact that the Thais celebrate this way. After all, we are not to judge local habits.
What is nonsense, is when those westerners who forgot to grow up, do the same!
Because, at least, Thai people will not target you if you are dressed for work like I was.
(There are actually laws for this, but not sure if they are being enforced).
But those stupid expats up north in Chiang Mai, they targeted everyone: the last thing you want is to be splashed by one of those, and then being denied in the Grab or Bolt you have been waiting for too long, just because you are wet! You also don't want to be splashed when you are on the way to the airport, because you don't want to get frozen by the AC of the airport or the airplane. And one of those western idiot had thrown a huge quantity of water inside the songthaew in which I was sitting when heading to the airport.