Why is Ricardo Lopez rated so highly by fightfans?

I know he retired undefeated but come on he never fought above light flyweight.

If he was THAT good surely he could have at least gone up to super bantamweight or something.

Dominating the minimum weight division shouldn't really be considered a great thing as the level of competition down there is hardly noteworthy, it's like being the best team in the Civil Service football five aside league, doesn't mean a whole lot in the scheme of things.

I admit I know next to nothing about him so am not stating he is overated just asking for people to tell me why he is not.

Did he beat a string of p4p stars I've not heard or something?