You can't get much more "major" in 5E 3PP publishers than Kobold and they have tons of martial options. It is fine to say that WotC has not stepped up to the plate on this one, but it is demonstrably false to say that "no one" has.A master swordman subclass.
An expert marksman subclass.
A dagger virtuoso subclass
A spear specialist subclass.
An axe axe subclass
A hulking hurler subclass
The problem is that the rule set was designed to have open space so that other publishers can go into the open spaces purposely left open by Wizards....
But no one did go in that open space for Martials. Every major publisher who didn't rewrite the whole books is printing blatantly magical warriors and casters.