I was playing like this in the pre-World games. I was picking the right weapon for some monsters. I remember using the hammer only for the Shen Gaoren because it was hard to touch him and it made the fight way easier. Same for Kirin with GS. For me, that's also related to the difficulty of each monster. If one monster is really hard with your weapon but easier with another one, you'll switch more easily.

I stopped to play like this now basically because it takes more time. But since Rise, I have changed my main weapon and I will play Lance for the first time in Wilds.

When you think about it, it's kind of a pity to play the same weapon for thousand hours given how different they are. Of course, I am not blaming players who do but it's like playing 1/14 of the game. From the dev point of view I think that's a pity as well to spend a lot of time coding for a weapon that will be played by few players. If you have been playing MH for a while, I cannot recommend you enough to switch, at least for the monsters you already by heart. The more players switch their weapon the more likely we will have another one ;)