None of those situations are bloodlusted 100% serious top tiers.
Now you're getting my point. Kaido MAULED the Scabbards when he got serious.
Issho was casual against Sabo and he literally said it. He used like, 40-50% of his power, tops.
Big Mom was nerfed and wasn't using ACoA or ACoC against the SHs.
Just like the Gorosei aren't going all out against the SHs.
And keep in mind, despite them not going all out, they STILL did most of their objectives.
Saved York? ✔
Took out Vegapunk and his satellites (sans York)? ✔ (only Lilith is left)
Stop the broadcast? Work in progress.. They stopped one of the most important parts of it, and judging from the spoilers they're close to ripping Emet apart and stopping it for good.
Find the Mother Flame? ✔
Marco was backed by the entire WBP
No he wasn't. By then Curiel was down, Ace was the newest item on the Krispy Kreme menu, Whitebeard was swiss cheese, and Jozu was a freeze pop.
He was left with Vista and fodders.
and Atlas and the weakhats are not Marco with the Phoenix fruit.
The SH are literally the MCs, if anything they're even more immortal than Marco, because Oda practically has a rule against them dying (sans Brook and Luffy who revived 5 minutes after).
Big Mom is an ass fighter.
And yet still a top tier who was stronger than everyone on the Sunny combined at the time.