I think before female hypergamy really took off after the sexual liberation movement, there may have been some amount of truth to the bluepill, or at least it may have worked for some people. Or perhaps it was just a way to cope until someone had success in dating by mere chance (which was a better chance before).
Then the advice just stuck around but as hypergamy increased (social media, dating apps), it became less and less successful. However, questioning it has always been politically incorrect, so I think there are a good amount of people who keep hearing this advice but it never occurs to them to question the status quo because to do so makes them unvirtuous/a bigot.