A malicious actor can utilize a botnet to skew the crowdsourcing of trust, for example. In other words, in a WOT for identification, one's identification can be invalidated or stolen by someone who purchases cloud time.
Web-of-Trust means there's a link between you and the other entity. The number of people who trust something is not really relevant, so crowdsourcing wouldn't matter. I know there was a service called WOT that relied on that, but in my opinion they were simply misusing the concept.
A pgp wot or the wot that you refer to can be subverted. In the scenario of everyone's identification, the WOT covers everyone in the population not a small WOT inside a relatively much larger population.
