I have one on my medical grade tank. Probably not needed but it's a nice separation point. The tubing from the filter to the stone gets cleaned and sanitized. The tubing from the regulator to the filter never comes off.
I found out really quick that if you get any moisture up inside that O2 hose you HAVE to clean it really well and blow it out with CO2. Within 3 days of using my tank for the first time there was black gunk just absolutely loving the higher O2 environment. I'm sure some of gas is trapped in the moisture and creates a feast for fungi.