Piccolo is weaker than the adult SSJs in the Buu saga. That's all you need to know about his power because anyone not on par with a SSJ was trash at that point. His standing is literally the same as it is by the end of the Cell Games. Dabura is on par with Perfect Cell. Even if Gohan did not go SSJ2, it does not matter because SSJ Goku gave Perfect Cell a run for his money, and Gohan clearly did not dominate Dabura in their fight. And if he was SSJ2, it's outright stated that he is much weaker than he used to be, so there's no inconsistency here either.While i agree with the super thing,as far as toriyama goes that holds true only till the Cell saga.
In the Buu saga you could not tell how strong Piccolo he is(outside that he is weaker than the ssj2),heck before BOG(in which we learnt where base Goku stands)you could make a strong case for him being weaker than the base saiyans including the Gohan that was weaker than the cell games,the same goes for other characters like retconing Shin's strength from the tournament on the way to Babidi's ship and the famous whatever or not Gohan was ssj1 or ssj2 against Dabura.
The Buu saga does not follow GT's rulebook, where a saiyan's base form can become stronger than a SS2. Majin Vegeta outright praises Goku after he becomes a SSJ2 by stating that he's become stronger than SSJ2 Kid Gohan (this is after 7 years of training). Hence, the scaling was exactly the same as the saga before it. You can indeed tell who's stronger than who.
In Super, I still don't know where Android 17 or Trunks stand. Are they SSJB level? SSJ3? Stronger than Mystic Gohan? I have no clue. Is Kale stronger than SSJB? But wasn't she getting smacked around by SSJG? Were Hit's constant improvements retconned? Does Base Goku have god powers? Was this retconned too? So are the Uni 6 saiyans (sans Kale) that much stronger than the Uni 7 saiyans or just as strong as their Buu saga selves? But wasn't SSJ3 Gotenks smacked around by Copy Vegeta, only for Base Goku to match the latter? But then Kale is able to fight Goku's SSJ2 form, so she's stronger than Gotenks?