I don't think Conor fighting manlets is the reason he's seen as mediocre versus a Holloway. Since Conor beat Holloway in his early 20's by decision, Holloway's won 13 straight fights. Think AS had the record at 17 though Jones would if the Hammill decision don't count. 13 straight wins and a 16-2 UFC record at 27 IS a godly achievement.
Conor also gets hate for the opposite reason as "fighting manlets". Dude gets hate for leaving 145 after flash KO'ing Aldo in a fight that really proved almost nothing, while at the same time holding the belt hostage. Holloway though fought Aldo twice and won hard fought duels with a legend. Conor since leaving 145 has fought 4 times and is 2-2 and was finished by Khabib(understandable) and Nate Diaz(not so understandable). He got a title shot after winning a close decision over Diaz and after getting embarassed by Khabib is going to get another title shot if he can beat Cowboy. The dude is very mediocre for the sort of oppurtunities he received and gets them because he's a draw and really the only million plus draw in the UFC and this is clear as day.
Conor's win over a super young Max Holloway is still the most brilliant thing he's achieved in his career and very few of his casual fans are probably even aware it happened.