As hunting cartridges go, the .30-06 rules sales by wide margin.
That said, the .300 WM has a strong following. I think, and that is just an assumption, reloading is not as strong overhere as in the States.
This I judge by the fact - that most components we are sold here are of US manufacture/brands.
Most cases I use are i.e. Remington brass or Winchester - even for euro cartridges like the 8x57IS.
Talk about weird.
Cooperate thinking and markets, I guess...
