You certainly can ban that IP.

It should be a balancing act though, somewhere between what you said and my first sentence.

Rate limiting, or additional layers of input sanitisation for IP addresses known to have been malicious in the past.

It's unfortunate that good users will have to endure some difficulties because of bad users on the same network, but if security is the priority, then measures must be taken, you shouldn't just leave to door open to potentially known bad users / traffic.

IPv4 is a shared resource, but some ranges have worse reputations than others, and all are owned by organisations that have the ability to monitor and filter for malicious traffic. It gets into a fraught discussion about censorship, but it is possible for network owners to monitor for, and block / restrict traffic detected as 'bad'. It's just a matter of cost and scale, and those that put the effort in should have their users rewarded with fewer 'trust-issues' roadblocks.