Eh Aldo was always just a good fighter, not a great one. For the longest time, UFC didn't have a featherweight division because they didn't think the lowest weight classes would sell, so WEC had that division and they just signed a bunch of bums who would fighter for lesser pay at the WEC level.
UFC then just took WEC's featherweight division and made it their own, they didn't go out there to find new top talent to sign. Aldo never truly beat that many UFC champion caliber fighters, except Frankie Edgar. Faber was a bantam weight, and he was a contender but not champ material.
Once UFC signed original fighters that weren't from a WEC lay over roster that could fight on a champion level, Aldo withered (McGregor, Max, and Volk). He then decided to go to a lower weight and use his size and even then he'll never be bantamweight champion.
Don't get me wrong, Aldo is a good fighter, but he's not great, and does not belong in the GOAT discussion. I was never on Aldo's train in being the GOAT despite how many times Rogan called him the greatest when he was FW champ. I know UFC propaganda when I see it, and Aldo as a elite FW was always UFC propaganda to make up for their crappy WEC roster.
Conor, Max, and Volk all exposed Aldo.