Btrees are not optimal for SSD, and the only reason we still use them is legacy constraints of page-oriented storage and POSIX block interfaces.We pay a lot of unnecessary write amplification, metadata churn, and small random writes because we’re still force-fitting tree structures into a block device abstraction.
I don't think we're disagreeing. But the issue is at the boundary between software and hardware, which the hardware device manufacturers have dictated, not further up.