As a developer, I can fully understand their decision not to support older versions. There’s a whole lot of effort needed to support old versions! Every little change you make needs to be tested in every version with potentially hundreds of combinations. Perhaps they could do it if they had very excellent unit test coverage, but even then they would need to fix things that unexpectedly broke. Also, instead of just switching to new function signatures when they make improvements, they would forever have to keep the old ones. It ties the code (and developers) into knots.
