What you call optimal performance with InnoDB, I call pathetically slow. http://www.lmdb.tech/bench/memcache/
And if you'd read the reliability references linked in the article, you'd see that MariaDB/InnoDB's reliability is the worst of many tested systems. LMDB's is flawless.
https://lists.openldap.org/hyperkitty/list/openldap-devel@op...
The one fault they found for LMDB, caused by fdatasync not updating the DB filesize, was actually a kernel/filesystem bug (fdatasync is documented to update the filesize) that had already been fixed two years before these guys did their research. Not an LMDB flaw.