Earlier quoted context omitted.
> sometimes the software is not compatible without the developer knowing it Sure, but this should be considered either a defect or something highlighted by a major version number jump.
Yeah, but who decides if it's a defect? Maybe the defect is subtle and only manifests in rare cases and the upstream rightfully decides that after a risk/payoff analysis, it's not worth fixing it. Or maybe he agrees and fixes it and it's included in distributions 7 years later. I've changed 5 jobs in 7 years (because of life circumstances) and I'm not even a job hopper... How is any commercial shop going to plan arou…
It's effectively part of insisting that it's properly Free software - if you can't maintain your own bugfixed fork, but have to keep going to an external organisation for their version, is it really Free?