@Kostiantyn-Tarasenko Most likely, because if you try to upgrade the wrong package, like e.g. some library that some Onion-devs' own package is dependant on, but that is compiled with different settings than the LEDE-one, it could render that package inoperable.
thanks a lot it solved the problem.
in the past i uncommented other stuff in this file but not the ones you mention.
Why the hell for the sake of new users this opkg update does not covers every source of packages that might be usefull when embarking on the journey with Omega.