You were comparing BM to Cracker tho.
Also "generally agreed as" is just a fancy term for consensual headcanon among the fandom.
The source to base poverlevels on is the manga , not general beliefs among fans.
Yep Cracker is Low High Tier, he isn't below that. While Big Mom is High High Tier. Both belongs in same High Tier.
I used to hear the "argument" to downplay Rayleigh is his stamina.
"But but he was panting after clashing with Kizaru for minutes".
While Big Mom has similar issue, hunger pang. Except hunger pang is worse. Being tired doesn't affect Rayleigh's mindset / brain. Being in hunger pang turns Big Mom which is not so intelligent since the beginning, into 3 years old girl level throwing tantrum.
While the "argument" to downplay Garp is his durability.
"But but pre TS Luffy hurt him"
While
1. Big Mom was not only hurt, but almost fucking died, not once but twice. First against Jinbe, second against King.
2. Exaggerated durability is more useless now because let alone top and high tiers, some mid tiers or even low tiers like scabbards already having ignore durability move, advanced CoA.