TL:DR; Anonymity helps a ton of people do things that they otherwise could not; for many many reasons.
Most people use that to grow themselves beyond what would otherwise be possible.
A minorty use it to be arseholes.
Letting the minority of arseholes absolutely ruin the benefits for everyone else is stupid.
Find a way to target the arseholes, and not the mechanism they're abusing.
This applies in all settings. People *abusing things other's rely on* is the problem, not the thing itself.