The biggest drawbacks are less support from quite niche packages (the ones that sets up its own homebrew tap), and a bit slower updates. But then I found it bearable much more than homebrew’s downsides.
[0]: https://macports.org
Last time I used it was back in the mid-late 2000s, before my technical capabilities were decent (could only barely write code and was basically clueless about the GNU toolchain and the like) and at that point, MacPorts packages were frequently broken and would sometimes remain that way for long stretches of time, with the only fixes being manually applied local patches (if they existed at all). It was very frustrating, and so when Homebrew came around and packages generally "just worked" I was an instant convert. I wouldn't be surprised if a lot of other people who were newbies during that time span have similar stories.
That was my experience as well a couple of years ago, with some quite painful OS transitions. Still, I’ve been using it for I think a decade now, and I cannot remember any problem in the last 4 years or so. It does not have everything as Homebrew is the cool kid and cool devs do not care about anything else, but it is solid. And last time I looked it had a much more sensible way of working than brew and a better security model, even if it leads to some duplication in the installed packages.
Regarding the permission problem: have never had any issue, but that's probably because I don't mix multiple users and developer tools.
I don’t even use Macports, but that’s just plain unfair.
Trying to judge the fairness of a technical aspect of a piece of software as a non-user seems rather pointless, don't you agree?
I was making an observation based on the fact that PowerPC Macs were discontinued in 2006 and homebrew was created in 2016.
So Macports (or other) could’ve changed things in the last 16yrs, which have been quite transformational for computers and software.
The difference in goals and tooling between the dpkg (Fink for macOS), ports (MacPorts for macOS) and brew systems seems to make all the remaining volunteers flow towards brew as the work required to fix ports is either harder, or getting the fix into MacPorts is harder. And sine Fink is dead, there is no dpkg-way to try out anymore.
I think RPM was never tried, and Nix is still an option but since you'll end up learning functional programming to use it, it won't get the hold the Nix-enjoyers seem to enjoy. Maybe Guix can inspire something, but I think the bar to entry with brew is really hard to beat.
The end result is broken and/or outdated ports, and even with the fixes post-macOS Forge the lack of content and port-fixes just makes it a non-starter when things like brew exist.