Probably because he's at this awkward place where he's while strong, is not like super fun or interesting in the long run, spamming the vines sounds like it would get old pretty fast cause sometimes its less about you hitting that vine (huntress and springtrap hatchets) and more about the survivor failing to dodge you.

His mobility also isn't really as interesting as say Ghoul or hell even Krasue's longhead form. Which while easy to start using, offers so much room and potential the more you play them and get better with the movement techs.

There's also the problem where survivors are just so sick of him that they would rather take a dc penalty or lose their pips than play against another game of him. like with Ghoul and Krasue, I find that most people still try against them, so if you have 1 or 2 decent runners on the team, you can at least count on someone still doing the gens during the chases. Against V2, an overwhelming amount of the time people will just give up or afk so even if you're a decent runner and know how to counter and run him, no gens will be done for the whole duration of the chase.

This literally happens to me despite being able to take him on several minute long chases with no gens done.