> Which is one of the reasons we have the whole world outside of them.
The other reason seems to be a failure to learn (or a belief in "this time it's different") the lessons from the 70s and 80s that informed many of the fundamental design decisions of RDBMSes.
The "NoSQL" world has had a remarkable number of incidents with ACID failures. Unsurprisingly, a fix involves sacrificing performance.
This isn't to say that the trade-off is never worth it. In fact, RDBMSes can and do offer such trade-offs as options. It's just not the default.
It may be accurate that RDBMSes are designed and "shipped" with default configurations that are ACID-first [1] (to coin a term), whereas the "world outside" is performance-first [2].
However, it's nowhere near accurate, and maybe even disingenuous, to suggest that SQL or the relational model somehow prevents high performance. The reality of the actual tools contradicts your claim, as the sibling comment pointed out.
[1] with the exception of early MySQL which defaulted to MyISAM as a storage engine
[2] as the joke goes, so is writing to /dev/null and reading from /dev/zero
