The suggested way to make the folder not writeable by the webserver with chmod 775 does only work, if the webserver is not in the group, the folder belongs to (which I think is a very common scenario). In a shared hosting environment I also had a case where the webserver ran with user rights, so not even chmod 755 would suffice. I would suggest changing the recommendation to chmod 755 though, because it should work almost always and maybe add a small warning for the second case.
The suggested way to make the folder not writeable by the webserver with
chmod 775does only work, if the webserver is not in the group, the folder belongs to (which I think is a very common scenario). In a shared hosting environment I also had a case where the webserver ran with user rights, so not evenchmod 755would suffice. I would suggest changing the recommendation tochmod 755though, because it should work almost always and maybe add a small warning for the second case.