Log-structured file systems: There's one in every SSD

The other major problem is effective control over when blocks physically hit
the platter, and which ones. There are no write barriers, the command to
flush the cache can't be queued, and Force Unit Access write commands
generally flush all other dirty data as well, making them slow to the degree
that no one uses them. All this stuff is important for reliable operation of
modern filesystems and databases, especially in portable devices.

I don't think do-it-yourself has anything to do with it - the question is
whether the person(s) concerned want to re-implement what other companies are
already doing with no obvious advantage, or do something that could
potentially run circles around current devices, if only due to the
flexibility and performance characteristics of the interface. A single level
filesystem ought to outperform one filesystem on top of another filesystem
every time.