I kind of predicted this in my SO post in 2019 [1]. They were falling behind for a while.
Here's how that works:
1. You see an announcement. "Foobar 2.0 requires Bazz 4.x"
2. You make a friendly suggestion that they not break backward compatibility with Bazz 3.x
3. If that fails, you volunteer to maintain backward compat yourself.
4. If they reject your patches, you hard fork Foobar and try to kill the original project, as they are clearly not good open-source citizens and must be replaced.
Volunteering to maintain backward compat. It can be very damaging in an open-source project. So let's admit you become the "redis 3.x" guy for Sidekiq. Now, every time the sidekiq project moves or tries to moves forward, they have to see with you to maintain compatibility ? Do they know you ? Are you already a contributor ?
Also, who really needs to stay on Redis 3 there ? Are we blaming Sidekiq for killing RedisToGo, A RackSpace company, because they didn't "have the time" to upgrade to redis 4 ? Sounds like business needs. Business needs are rarely good open-source citizens.
How does backward compatibility mean a project is unhealthy?
> Do they know you ? Are you already a contributor ?
How is someone who shows up and volunteers to help not a contributor by default?
> because they didn't "have the time" to upgrade to redis 4
Time is money, and when you reach a certain amount of money, your business stops being profitable. So yes, presumably they literally didn't have "time" to do so.
It doesn't mean it is, yes. Compat or not isn't a "healthy metric" at all.
>How is someone who shows up and volunteers to help not a contributor by default?
As a maintainer of a serious project, would you accept a PR adding back backward compatibility, with the premises of "i'll maintain it", from a random person ? It's not an healthy decision at all for the project to accept that, actually, depending on the project and the implications.
Sidekiq didn't kill RTG, they chose to die.
RTG decided not to offer future versions of Redis past 3.x. Once the owners stop investing time and effort into a company, they're choosing to let it die while pocketing any remaining profit.