Homebrew is one of the few open source products that is really marketed well. I don't use it, but the brand recognition it has created for itself is really commendable, and something that most opensource developers should learn from.
I honestly think the big thing was attempting to discredit all of the alternative package manager solutions using half-truths. I remember the big ones were everyone claiming that Fink and MacPorts were nigh unto incompetent for 1) not having binary packages (even though they actually did), 2) packaging too much stuff (which was a hard-earned lesson from Apple breaking their system dependencies and something Homebrew later started doing as well as time went on and they learned the same lesson), and 3) installing to non-standard folders (which Homebrew also finally was started doing as of recent versions of macOS on "Apple Silicon": I set up a new macOS system for the first time in years and I burst into laughter when Homebrew told me where it was installing everything... it frankly should have had a little personal apology to Fink/MacPorts in the console output).
In any forum (SE, Reddit, HN etc.) whenever someone mentions the need to install a package the HB developers / product manager(s) create a post suggesting Homebrew along with the command on how to use it. They rightly targeted newbie programmers. Good marketing is indistinguishable from word of mouth marketing. In fact, once marketing achieves a critical level of user-base, good marketers shift to create strategies to promote "word of mouth" because of how effective a genuine referral from an existing customer.
LOL! He did talk a lot about his programming backstory (played with BASIC as a kid, no formal training, chemistry major, discovering Linux) and how this informed his worldview. Bottom-line, he is very results-driven and I think he has a good point about how a lot of tech interviews screen too much for theory and not practice. Turns out you don't need to know how to invert a binary tree to build the most successful package manager of all time :)
Yeah, they targeted newbie programmers and convinced them their approach to package management was superior. If I remember right, it was finally Apple itself that indirectly forced them to change their install directory and install packages the "unix" way, by making changes to macOS.