I didn't know people hated it. But this forum bears mostly teenagers, so an old sitcom like F.R.I.E.N.D.S may be dated and alien to them. They compare it to current TV shows, unaware that most of their favorite sitcoms take inspiration from it.
Because they resent its impeccable receipts (all ten years in the top ten, the last nine in the top five, one at #1, Emmy Award winner for Best Comedy Series, fourth most watched series finale of all time) and covet them for their own faves.