Yeah, I agree to certain extent. I suspect a lot more depends on the individual rifle with WSM extraction, as in how slick the chamber is, how square and polished the lugs are, etc. But in my rifles I've found the above loads work fine.
In reality I like the .300 H&H better than the .300 WSM. It feeds and extracts really easily, and has the same case capacity and hence ballistics of the .300 WSM. But try to find a .300 H&H in a light rifle. And try to find .300 H&H brass vs. .300 WSM.
Of course the rational solution is either a .30-06 or a .300 Winchester. But damn they're boring.
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