"We're the job board that forces you to jump through hoops to provide evidence of how active your hiring process is" isn't a sales pitch particularly likely to attract employers (in which case there's not much incentive for candidates to pay them either). And even if it did, it wouldn't replace Glassdoor' reviews - with all their inadequacies - for people that care more about whether the employer sounds better or worse than their current employer than whether they will get a job offer by the end of tomorrow.
