I've upgrade S.u.S.E installations since my first version which was 5.2. That was in 1998. This was coincidentally also the year when APT was released. So rpm based distros allowed updates "forever" as well. Most probably even with a definition of "forever" that is longer than the one for APT.
Posted Nov 22, 2012 23:20 UTC (Thu) by anselm (subscriber, #2796)
[Link]
Debian allowed upgrades from one version to the next even before APT came out. I have a Debian installation on one computer that I made around 1995 or so and have only upgraded since (with an occasional »cp -a« to a new machine). This includes upgrades from a.out to ELF and from libc5 to libc6.
On the other hand, doing SUSE upgrades was touch-and-go. For example, the first SUSE I had was 7.3, and going from there to 8.x was practically impossible. At the time even the SUSE people we had to deal with recommended doing a full reinstall instead, which went faster and broke less stuff.