I think if a Web of Trust becomes common, it will create a culture shift and most people won’t be excluded (compared to invite-only spaces today). If you have a public presence, are patient enough, or a friend or colleague of someone trusted, you can become trusted. With solid provenance, trust doesn’t have to be carefully guarded, because it can be revoked and the offender’s reputation can be damaged such that it’s hard to regain. Also, small sites could form webs of trust with each other, trusting and revoking other sites within the larger network in the same manner that people are vouched or revoked within each site (similar to the town -> state -> government -> world hierarchy); then you only need to gain the trust of an easy group (e.g. physically local or of a niche hobby you’re an expert in) to gain trust in far away groups who trust that entire group.