Trust in the real world is not immutable. It is constantly re-evaluated. So the Web of Trust concept should do this as well.

Also, there needs to be some significant consequence to people who are bad actors and, transitively, to people who trust bad actors.

The hardest part isn’t figuring out how to cut off the low quality nodes. It’s how to incentivize people to join a network where the consequences are so high that you really won’t want to violate trust. It can’t simply be a free account that only requires an a verifiable email address. It will have to require a significant investment in verifying real world identity, preventing multiple accounts, reducing account hijackings, etc. those are all expensive and high friction.