All of the advantages of Maemo (except the online "upgrade", more on that below) are not courtesy of Nokia, but of the user community.
I'm sorry but that's just hyperbole.
Nokia and the Maemo community aren't two separate things, Nokia is part of the Maemo community. They don't just sit there cherrypicking the hard work of others, if they did that no one would contribute to Maemo at all.
Many of the applications in Maemo Garage were written by full-time Nokia employees, and AFAIK the Hildon interface was written entirely by Nokia employees.
The USB host feature is a non-Nokia enhancement
Actually that's not true, the USB host feature is built into the tablets themselves. Nokia hasn't advertised it, but it's still there.
The only thing that third party apps like USB Control do is switch host mode on, but you don't need them if you use a USB adaptor that has the correct power layout to activate host mode.
even the repositories are one giant mess
I don't know which repos you've been using, but the official ones work fine.
If you stick to the official ones (the ones that come with the firmware by default) they work very well, and the update system works well too.
You don't have to use the App Installer to get apps, at least not directly. You can browse installable apps at maemo.org/downloads and install them just by clicking on the green arrows next to them.
Oh yes, the online "upgrade". I'm one of the unlucky who tried that "upgrade" and ended up with a tablet that is not only not upgraded, but stuck in the old formware, with only the option of -- once again -- reflashing the tablet and installing everything from scratch.
I'm sorry to hear that, but it worked absolutely fine for me on both my N800 and N810. And even if OTA didn't work for you, the flashing should work, so you will get the update one way or another.
However, you're completely missing the point the article is making. It's not about the update method, it's about the update being available at all:
When OS2008 was made for the N810, Nokia also made it available for the N800 and (in an unsupported "hacker's edition"😉 for the 770. In other words all maemo tablet owners were able to use the latest version of the platform.
This kind of thing just does not happen with S60. When S60 3rd FP2 came out, Nokia didn't make FP2 available for FP1 phones, even though FP1 phones had very similar hardware.