It existed before dyslexia specific fonts existed and there was a dedicated effort to create them.

It became popular early on for dyslexia because it just happened to be really useful for dealing with the issue.

Compared to a specific font designed for dyslexic people it doesn't hold a candle to it. But that doesn't make it bad for the job either there's a reason it got popular for that usage in the first place.

For like a good 10 years it was basically the only good option. Nowadays there are just much better ones and anyone still using comic sans I would hope it's just using it for silly things.