Exactly. Who's hurt more if it's hard to tell who the real celebrities are on Twitter? Whose press is worse when a celebrity is impersonated by some asshole on Twitter—Twitter's, or the celebrity's? Maybe initially the celebrity, but I'm gonna say it's Twitter in the medium-term. Who's gonna be hurt by "Twitter has an impersonation/fraud problem" headlines?
Whatever else the blue checks are, they're also a solution to a problem for Twitter, and those blue-checks and their activity are a huge part of why everyone else engages with the platform. If they make people pay, they better hope the adoption rate is incredibly high among existing blue checks (who cares about the unknowns who pony up for it, in addition) or they're gonna be in for a bad time.
Whatever else the blue checks are, they're also a solution to a problem for Twitter, and those blue-checks and their activity are a huge part of why everyone else engages with the platform. If they make people pay, they better hope the adoption rate is incredibly high among existing blue checks (who cares about the unknowns who pony up for it, in addition) or they're gonna be in for a bad time.