Debian did none of these (at the time), it was a text installer which asked loads of questions I didn't really understand, and didn't install X or gnome or install wireless drivers by default.
Of course, I suspect the things you had to do to Debian to make Ubuntu wasn't very much -- just hide lots of installer options behind an 'advanced' option, and set a bigger set of default packages to install. But it was enough to help me get into Linux.
Sound and video playback worked out of the box for far more cases than with Debian. Networking just worked for far more network cards. X just worked the way you expected it to in many more cases. And while it certainly was buggier than Debian Stable, I don't recall it being buggier than Debian Unstable on which it was based.
Network drivers for anything other than an intel card. Still, to this day. They're not in Debian for philosophical reasons, but they're a pain-point to non-expert users.
(If someone wants cheap and simple nowadays, I recommend Chromebooks. But if they need free, as in I can re-use some of the flow of decommissioned machines from work, Ubuntu it is!)
I've heard this before, but I don't buy it. I have been using Linux for 20 years now; back in the day, and back when Ubuntu came out I was using it on my desktop (today, not so much) and I simply not believe this claim to be true. It's often repeated, but never with concrete specific examples on what was more polished and how it was more polished.
In fact I believe the opposite to be true. Back then I was using Debian on my desktop. I naturally tried Ubuntu and found out it was less polished because it contained more bugs.