The purpose of the checkmark is to denote a Public Figure, but Twitter doesn't seem to follow any specific rule about who is and isn't a public figure. Subsequently, there seems to be a lot of bias, as many verified users are nobodies like hot take "whities-are-bad" journalists or people who advocate a certain political agenda.

The blue checkmark was seen as an indication of someone significant.
Now it usually mean verified idiot.

Three dislikes? I didn't know we had some verified Twitter users here!