checkmarks ALSO mean you are who you say you are. making them a feature of Twitter Blue (note: one feature of Twitter Blue) eliminates any status that might have been conferred in the past, yes, but it also goes a long way to sorting legitimate from fake users.
They are who you say you are - assuming you can do proper verification of individual identity and affiliation, authorization to represent a business or brand, etc. for some portion of that first $8 payment.