Someone else can always offer 20% more than you if they use you to train. This may work on the small scale where you build lasting relationships, but on the scale of large companies? You'd rapidly gain a reputation of being a springboard, and not a place people join to do their best work.
I'd argue we'd gain a reputation of being really good, and that we improve together. That's not something you can buy. It might not be obvious, but while creating a great agency, this also implies creating a great workplace of my own. So if I feel like abandoning ship I know I have to change something.
Also, what's better than building lasting relationships? I'd stay "small scale" awesome anytime over being just another asset of a "large company".
I'd argue that we live in a time where you don't have to be "centralized large" anymore to achieve big things. Rather we should figure out how to do even better with loose organization paradigms.
