A milieu is the culture contained in your unique set of connections.
It is an ever-shifting, individual configuration of information flows. The Twitter feed you have curated is a milieu. Your friend group (which is not the same as the friend groups of the other people in that group!) is a milieu.
Selecting these sources and crafting that culture is a form of taste
What sets Frusciante apart as a guitarist is that he is uncommonly undistractable (“he can really focus and concentrate and apply himself to his craft in a way where the noise of the world has less of an impact”). In the words of this essay, this can be rephrased as: Frusciante has an uncommon discipline about what he lets into his senses; he is uncommonly deliberate about curating his milieu
He knows how their playing styles interrelate and where he wants to position himself in that landscape of playing. He has a map of guitarists. The map is organized by technique but also by the effect they have on him, the kind of songwriting they open up. He tweaks this web of influences to change his playing.
Speaking with authors through their written work triggers the same neural circuits that produce imitation of desire. By stocking a bookshelf judiciously, you can express a preference over preferences — “what should I value? What do I want to spend my waking hours thinking about?” — and act on it through careful, honest reading. This engineering is safe: most authors exert their influence slowly, over hundreds of pages, and if the effect turns out to be undesirable, you need only put the book down. It’s cheap and reliable — if you want to emulate someone, start by reading what they read. Most importantly, it’s powerful, because authors form a large part of the meta-peer group that determines which communities and games you engage with.