I dont know how to feel about the suggestion to ban knock off. Its a really spammable move but so is scald and stealth rocks, did they ever get banned? No.
The major difference being that you can undo the burn from scald with a cleric or switch into pokemon that don't care about a burn (magic guard, storm drain, water absorb, things that don't rely on staying alive indefinitely or physical attack). Stealth rock can be countered (Magic bounce). Canceled (rapid spin/defog) and does not do damage. Giving certain pokemon a free switch in, contrary to switching into knock off, taking large damage and getting grippled
I'm also varly certain that without the boost (and say about 80 BP) if knock off only had a 30% chance to knock your item off (comparing it to scalds burn) and had immunities, we wouldn't have much problems dealing with it
Major difference being, if my special sweeper is keldeo, he wouldn't mind switching into scald and potentially getting burned, it does not make him any worse at sweeping, since hes a special attacker. Contrary to Knock off, where the power is high enough and the distribution is wide enough to where the only things capable of tanking the high power STAB knock offs are full fledged tanks, and most are reliant on their item to stay in the game as long as they need to be. Even if I bring an attacker in that resists it, losing potentially my scarf, band or life orb is going to leave me a bit gimped, because not either my damage is lower or I'm not fast/strong enough to deal with the threats I'm designed to take out.
To summarize the main difference between scald and stealth rock and knock off is knock off's ability to negatively effect essentially every competitive pokemon in the tier with little to do to reverse or prevent such effects. With the few counters being either not tanky enough to deal with the sheer damage or just a wall with no means to counter attack effectively.