> "I'm wondering why they didn't just use lubuntu"
They could of, and that might have been a great idea. Although not as headline grabby as "we made a new OS!". I think that Debian probably is slightly better on PIs simply because Raspian has been running off Debian from just after the first Pi's came out, and since Debian historically supported more architectures, so maybe makes more sense from stability standpoint to build off of Debian instead of Ubuntu. I recall the creators of Raspbian saying it was actually quite difficult as it was to port Debian to RPi 1 due to the particular architecture, so starting from Lubuntu might have been a little too difficult.
Ubuntu dropped ARMv6 a long while ago and refuses to consider bringing it back, so it was out of the running as a Raspberry Pi OS, back when just the Pi1 was around.
Ubuntu will run just fine on the Pi2 and 3, just not on the 1 or 0. Pixel is a mildly-tweaked version of LXDE running on Raspbian, which is a mildly-tweaked version of Debian. That's problematic, when part of their brand is providing a good environment for learning (which is helped by keeping the OS as similar as possible between different versions of the hardware).
They could of, and that might have been a great idea. Although not as headline grabby as "we made a new OS!". I think that Debian probably is slightly better on PIs simply because Raspian has been running off Debian from just after the first Pi's came out, and since Debian historically supported more architectures, so maybe makes more sense from stability standpoint to build off of Debian instead of Ubuntu. I recall the creators of Raspbian saying it was actually quite difficult as it was to port Debian to RPi 1 due to the particular architecture, so starting from Lubuntu might have been a little too difficult.