At least we see him progressing one step at a time from Doflamingo to Cracker to Katakuri to Kaido. And he had to fight and lose to earn his power ups
Sanji went from getting owned by a genie to fighting against Queen in base and Zoro got stronger offscreen. And let's not talk about being gifted Enma and the raid suit, especially the raid suit which was a completely free powerup with no drawbacks
Luffy and the crew getting stronger in a very short time doesn't make much sense compared to the other top tiers who spent years in training. But it had to happen because the plot can't handle another timeskip
Sanji went from getting owned by a genie to fighting against Queen in base and Zoro got stronger offscreen. And let's not talk about being gifted Enma and the raid suit, especially the raid suit which was a completely free powerup with no drawbacks
Luffy and the crew getting stronger in a very short time doesn't make much sense compared to the other top tiers who spent years in training. But it had to happen because the plot can't handle another timeskip