In fact we both don't understand each other. I was wrong about the horn part. Right he broke it via Almighty but later when Yhwach takes ichigo's powers. Ichigo says that his powers were disappearing. His hollow powers mixed with his quincy power. Which is weird and I will explain why. Before that
https://**********.com/read-online/Bleach-chapter-683-page-4.html
If you look clearly then you can see Left hand of renji and the third hand are synchronized. Even when they are broken/cut they are same. It is highly possible that because Yhwach cut his bankai in the future and via synchronization his hand was also cut in the future.
So that cannot be used as the proof that Yhwach's Almighty can interfere with physical body directly.
As for ichigo's horn it directly says that his source of hollow powers that were mixed with his quincy powers were disappearing. So Again that was an external power.
Maybe that is why an ichigo who had lost most of his external powers and just had his shinigami powers was more useful.
His statement that "the blade is me" would make more sense.
Since now that everything external is gone the only thing that is left is The blade and Ichigo as a singular being.
That also explains that why Ichigo's Bankai wasn't Broken again. Just the external guard was broken.