The CA system, on the other hand, has more or less abandoned the expensive, manual "extended verification" process in favor of the zero marginal cost "domain verification" process. This switchover drove the cost of a new cert to $0 for almost all users.
So I'm really not following your analogy, since Twitter gave up the workflow and started charging (aka, a cash grab), whereas CAs gave up charging and adopted a more efficient workflow (aka the expected behavior of efficient markets).