While i agree that a standard is useful, i think the FHS is out of date: it has lot's of fragmentation where it is not needed anymore, instead of keeping it simple. And also lots of reinterpretations, which makes it even more confusing.
Which results in some people who learned FHS thing (but never why it happened) keeping slave-ish to it and doing nonsense in major distros. Which, again, results in small niche distro being forced to it too, because they lack the manpower to adapt the tooling.