You are looking at it from the wrong angle. Its easier to give Akainu AdCoC or create a narrative around magu magu than to make Akainu a D, connect him to void century/Imu, etc.
Just for clarification, I don't think Akainu has a better final villain argument over Blackbeard even if you ignore power levels.
What I'm saying is other characters can fill that Final Villain place BB takes up (Imu for example) therefore you can legit make the argument Luffy vs Blackbeard isn't more guaranteed than Luffy vs Akainu (ignoring BB's power potential). Not final villain status, but a fight at any point.
Regarding Akainu's connection to the endgame plot. Oda made Law a D well after his introduction, we hardly know anything about Akainu, molding the plot around an unexplored character would be easier than tampering with his power level given we know it took 10 days and extreme diff to beat Kuzan. Akainu has already been established as a peer to the top tiers today, even if he's the strongest of the bunch, he doesn't have the potential separation that Teach, who is growing, and has an unusual body (which makes him an anomaly), has.
Is it impossible? No not really, Oda can make Akainu take some hax ability (maybe something from Imu, or Bonney makes him younger etc. etc.), but it is still harder to do than give him the right connections as a character, given we know little about him.
Cry more, Roger became PK only with AdCoC. Just because your favorites will never get CoC, you dont have to downplay it lmao
Roger is a fodder in the final villain debate. That's not final villain status lmao. He's run of the mill, dude found the likes of Garp and Sengoku challenging, and could never defeat Primebeard.
He never stood head and shoulders above other top tiers, your scope is far too small.
You know how many Big Mom fans believed she will be back in the story to get beaten by Luffy?
Ask Ndule or Steven if you don't believe me
LMAO who gives a shit about the 0.0000000000000000000001 % of Big Mom fans in the fandom. Every casual and their mother has wanted Luffy to beat the shit out of Akainu for ages, Oda obviously knows this, he did that on purpose. Only recently after the Kaidou fight has there been some pushback from power level junkies who can't stand the fact that Akainu will come after Kaidou, that has no impact on Oda.
Sabo beating Akainu would be like Ace version 2 coming back to life to beat Akainu
Sabo has an argument, but Luffy is the main character, and no antagonist in One Piece has traumatized and impacted Luffy more than Akainu. Akainu is the leading reason/figure of why Post timeskip even exists, he has changed Luffy's design forever, and he destroyed Luffy's will. Then you factor in that Luffy has stated he needs to take out Admirals and Yonkou to surpass Roger, well he already dealt with the Yonkou side, he has yet to deal with the strongest Marine.
