How to choose a collector resistor value for a common emitter circuit according to the output resistance?
Usually, the external load is coupled to the collector via a dc blocking capacitor so, this means that the nominal dc bias point at the collector is unaffected by that external load. That is noteworthy for most designs of CE amplifiers.

Now, ignoring dc conditions, a fairly accurate assumption is that the ac gain is Rc/Re. If an ac impedance is across Rc then the gain effectively lowers. So, you choose a value for Rc that swamps the external impedance and the rule of ten is fine but can easy be a rule of 1 to 1 in many designs when impedance matching is important. If you study the common emitter amp, a decent approximation to the output impedance is the collector resistor, Rc.