It's amazing the misinformation some old timers spread around as gospel. Thankfully we have the internet and can read, read, and read some more. Then make our own decision with the materials available.
You should hear some of the rediculous things some people in the autobody trade try to pass along
I mainly only use perlite in pots unless I have some used soil I need to get rid of I'll mix it into the ground. Steer manure is King out in the yard along with Redwood mulch.
Mike