Cononical should really keep the old repos up for longer. At least the parts necessary for upgrading to the next version. 19.04 is barely over a year old. It's entirely reasonable for users to leave a computer for a few months and expect it to still work when they come back.

Sure they could use LTS but that has the same problem, just on a longer timescale.

I could turn on a PC with the first Windows 10 beta and it would update to the latest Windows 10 no problem. There's no reason Ubuntu can't do the same.