Huh, interesting. I could have sworn that the “block of crystal” thing I had N years ago was an antiperspirant and not just a deodorant, but it’s been a while and I can barely remember what happened last week. I just remember that it was some aluminum salt or another, but thought it specifically wasn’t alum (which I still use for small nicks and cuts)
My guess would be that’d depend on who’s calling it “natural”. You definitely do see that meaning here as well, even in the same store