I can understand that. But it's largely because Kubo reserved ALL his top tiers peak power for this final arc. Yamamoto was and is the only top tier we've seen get very serious. Shunsui and Zaraki and the like have been serious but not to the point of bankai and in Zaraki's case, before he became top tier. However whether Yama is 10s of thousands or 10s of millions or anything Inbetween, it doesn't matter much in regards to Akainu. He's not that hot and magma can't even get that hot. I'm not so much trying to prove Yama is 15 million degrees C, I'm just saying he's hotter than Akainu.