Earlier quoted context omitted.
"Someone else would have filled the void if homebrew hadn’t shown up, and it would hopefully have been better." MacPorts and fink existed before homebrew took over, and they weren't better. That's why homebrew took over.
But Homebrew wasn't (and isn't) better than MacPorts, either. They both work well (we can and do quibble about the internal mechanics of each), and appeal to different groups of people. My theory is that Homebrew was announced at exactly the right time in the MacOS adoption curve. A huge number of new users arrived with no existing knowledge of MacPorts or Fink. Most of them didn't know they needed a package manager…
I might have liked MacPorts with my current experience, but when I first needed to install CLIs and tools I did not have extensive knowledge of shells and paths and such, and MacPorts felt significantly less "integrated" especially when something would fail (as opposed to brew occasionally just asking if you want to overwrite symlinks essentially).
I'll never know if MacPorts was better once you're past the initial hurdles since I'm so used to brew these days, and I believe that sort of experience is probably not isolated. Given the propensity for Mac users to want something that just kinda works and gets details out of the way, I can see why brew succeeded.