Well, I very specifically do not want to use installer software.
If Pale Moon wasn't portable I would not have given it even one second of my time, regardless of how good it might be.
I have been trying to replace all of my used software with portable alternatives for years, even up to the point of thinapping stuff like Excel. So no, the installer is not an option.
My main reason for wanting to use portable software is because I detest the fact that installer software clutters up a system with all kinds of useless folders and files scattered around. It also makes it very annoying to do a full OS reinstall since it means you'll have to reinstall the software as well and also reset your custom settings.
I have been using Opera for about 10 years and in the last 5 years I used a portable version. I was very happy with it until the devs started screwing up the browser, making it bloatware and removing much needed customizability. I've resisted upgrading Opera for some time but now the older, no longer supported, versions have problems with the changing environment. New Opera is a no go and therefor I have been searching for an alternative. Tried a few, discarded them, then came to Pale Moon, and it's absolutely great. Better than all the other browsers I've ever tried. No joke. It is lighting fast and does almost everything I want from a browser. And it seems the FF add-ons have become at least as good as Opera's, which wasn't the case last decade. So it's highly likely that i'm sticking with it.
Now, I came to Pale Moon through a review on some site that turned up in a Google Search and just installed it and tried it, so I don't really know what your exact goals were with this software. I just used it in the same way I would use any other browser and the few problems I had I posted here, like this one. So when the response is "it's by design" I don't really know what to do with that.
You say
Part of that design is that there should never be any assumption about the host PC and what folders exist or don't exist. It also means that it will attempt to not unintentionally end up leaving files or data on the host PC.
Fine. That's your choice, of course and I'm sure it's consistent with your goals.
But why? Really!
Is it supposed to be like an incognito type of browser, like Tails, minus the Tor stuff? Or is there any other reason?
Because, you'll have to agree that from my perspective, it's annoying that I cannot have a custom default download folder in my set up, right?
From my point of view, and for what's it's worth, because I'm not the developer, just one user, so take it as you will, this:
Part of that design is that there should never be any assumption about the host PC and what folders exist or don't exist.
should be nuanced by adding "unless a user specifically enables the program to do so in certain instances".
To me that would make so much more sense.
Going back to the problem I have with installer software where it tends to create all kinds of unwanted folders, you know, the stuff in roaming/local/user/whatever. I hate that stuff, I'm very able to keep my own data system and it's much better and easier to navigate. Now instead of creating these folders like installer software does Pale Moon actually comes with it's own folder
and forces me to use it. To me that's 99% the same thing. The program decides, not the user.
I have had my main download folder in a specific location for over a decade. Not only am I used to it being there, there are also other things that depend on it being there. My torrent client scans that folder for new .torrent files. A bunch of selfmade Autohotkey scripts work with that folder to collect data, clean it and do other stuff, and so on. Of course, I could change all those things to have them work with the ready made Pale Moon/Downloads folder, but why would I want to do that? I'm not interested in making all these changes just because some piece of software forces me to do so because that software is designed so "that there should never be any assumption about the host PC". I just don't see the argument in there.
Having said that, it's a minor thing, I could live with it, because Pale Moon's advantages outweigh this annoyance. I just wanted to illustrate for you how this is perceived on the user's end. Maybe that's something you will value and maybe not. Both is okay.
In fact, since I edited the config file, my problem melted away and I'm very happy now.