This argument isn´t worth having unless the following can be accepted as a common ground:
Oda has characters reveal new abilities all the time, not only Kuzan but also Doffy, and even Luffy at the start of the timeskip. People believe characters like Blackbeard(multiple personalities sealed inside of him, DF awakening, advanced Haki), Shanks(A DF in his sword) Mihawk(advanced Haki),Sakazuki(Advanced haki and Awakening) when none of them have showed it in the actual manga, despite having significantly more screentime than Aramaki
Aramaki has had very very little screentime at this point, the equivalent of what Kuzan got in W7 and Kizaru had at Sabody. We can act like reverie was his version of MF, but that shit was like 5 pages and a sideshow anyway. We don´t even really know what happened with Aramaki and Fujitora even, and Oda offscreened Aramaki vs Weevil. We basically know nothing about the man, beyond his respect for Sakazuki, and belief that the CD´s maintain order by discrimination.
Aramaki hasn´t gone all out at in any point on screen, he said he was finally going out right before Shanks arrived in Wano, and in Reverie, his goal was to find the RA leader, not stop Morley
He has had a legitimate interest in restraining his opponents in both Wano, and at Reverie. You can say it´s dumb or whatever, but his goal in Wano was tracking down Luffy, and his goal at reverie was finding Sabo.
Oda hasn´t ever said that Mihawk was the only black blade user alive, leaving the possibility for others. I doubt Oda will spam it, but thats how these special powerups are treated in Shonen. Yamato literally has the same powers as Joyboy(awakened mythical zoan, and ACOC)