Definitely legal and definitely any musicians' obligation to know their business (although for some reason that's a relatively decent concept).
But Lion could be a bit gangsterism about publishing. He dropped Horace Parlan because of a dispute over a Ronnie Boykins tune. There's a few other things I've heard .
And AFAIK, the "junkie label" era Prestige never shared publishing. Same for Savoy, etc.
It was all legal, it was all accepted business practice, and too many musicians were just oblivious to any of it. But the businesses definitely enforced their advantage in an often heavy-handed manner. One should certainly understand ill-feelings decades later.And it's not just LaRocca btw, nor is it just jazz.
50% of your money is not insignificant, no matter who you are. Leverages should be fully understood and mutually exercised.