Not certain about your point... but if you meant SELinux should be turned off, then you got it wrong, I think. SELinux is more like your Firewall. You don't turn your firewall off because some software you are trying to use does not work!
I agree with you. SELinux should be on by default much like a firewall, but I guess I was referring to packages not shipping selinux policies leaving the user in limbo about why the software which is documented to work out of the box does not.
For as long as you've got official articles like this[0], it's a harder sell than it should be.
[0] http://www.asteriskdocs.org/en/3rd_Edition/asterisk-book-htm...
When you want users to use your software by default, users should not need to touch it by default.
Sorry about your luck selinux, probably not your fault.