There are many reasons to hate pol.
1. Commies hate pol because they have zero tolerance for them. They are so assblasted that they even made their own board on infinity chan.
2. Redditors, 50+year old boomers, and underage new fags frequent the board.
3. Caused the majority of the memes made between late 2015 to early 2017 to be purely political.
4. Half of the board is ironic shit posting, larping, or ironic ideological impersonation. That shit gets old fast.
5. Some people fear that /pol/ is so controversial and involved in US and Euro politics that it may result in 4chan getting banned around the world.
6. Many conflicting ideologies that make up the bulk of /pol/s users hate each other. Mainly being: Natsoc, Ancap, and Republican are typically at odds with each other.