>>149545904I'm a total sucker for glasses and mousey girls, and even I will admit that Daphne is a good character. She was massively overshadowed initially just because she and Fred were originally the bland, normal ones to create a fun contrast with Scooby, Shaggy, and Velma, who were the real stars of the show. But she's never been a slut or a jerk or anything, she's relatively nice and humble, just kind of generically extroverted.
Then, like
>>149546332 said, she (and Fred, but we're just talking waifus) got some actual characterization beyond trying and failing to solve the mystery offscreen while Velma figures things out and Shag and Scoob dick around. Add in the contrarianism that contaminates the internet like lead during the 50s, and Daphne gets a surge in popularity.