Also users behind large NAT gateways (colleges/dorms, apartment complexes with IOS contracts) or CGNAT (most mobile users including 5G hotspots which could be a primary internet connection for a household) will often appear to be behind one or a handful of IPs, and not only does blocking one block them all, but blocking a gateway IP that is part of a pool might not necessarily block the intended user at all. Also as was stated, it’s trivial to get a new IP either via VPN or, sometimes, resetting your modem.

IP bans are often not effective.