Obsolete? v4 still works on the operating system that was current when it was first released, as well as the next three operating systems. It works on the operating system that was Apple's latest and greatest one week ago, the operating system that's still installed on the majority of Mac, and will still be supported by Apple for years to come.[0]
My company insists that I shouldn't update to High Sierra because doing so breaks several well-known apps, including Microsoft Office (albeit v2011, I think?). So I haven't updated, and... everything is fine.
A demand for a free upgrade path suggests to me that all software ought to be sold as lifetime licenses with unlimited upgrades. I think that extreme would undermine our whole industry far more than a company insisting that only their latest product is supported on the latest operating system.
[0]Here's Apple release updates for Sierra, El Capitan, and Yosemite very recently: https://support.apple.com/en-us/HT201222