Deran, I'm not sure why you say this.
Breeding means moving towards a well defined target, regardless of whether you use established lines or inject something new into the mix.
Look at other plants: If a potato breeder (say) wants a new variety that will do such-and-such, of course he will use an established variety that is close to his target, and then perhaps try to import some new and desirable traits.
I am sure that people travelling, sourcing new material, and trying pot luck mixes are VERY useful, but that's not necessarily breeding, even though we might like to think of it as such, because of a romantic image. The real breeder is the one that does huge selections, documents his work meticulously, then chucks away maybe 95% of his work (rather than dumping it on a gullible market), determined to find the ONE he's really after. Yes, he must have good instincts, but good instincts without backing facilities make a pollen chucker, not a breeder.
I doubt if most of the names mentioned would come anywhere near deserving the name of breeder.
The illegal status of cannabis makes it quite difficult to be a real breeder.