Yes, the "Disable Location Field Style Note" does not seem to work all that reliably.
Like you, I always have the FamilySearch locations turned off, using the field memory of my browser. So every time I close my browser I have to hide the autolocations.
When this new setting appeared, I immediately checked it to "off" - this did not have any adverse effect. But after your comment here, I have tried turning my browser off and on again - and the setting does not seem to hold; I still have to turn it off manually from a profile at the start of a session.
Edit: perhaps it means something else?
I tried it again, logging out and restarting the browser. The box in the settings stay ticked but has no effect in the profiles.