If you release a product for a platform you have to keep up with the APIs on that Platform. When OpenGL support was removed from OSX (now macOS), Frontier should (could) have re-coded to use Metal. Frontier just didn't see enough return on that effort so they dropped support for Macs, simple as that.
At some point DirectX11 will be dropped and they'll have to recode to DirectX12+ for Windows / XBox.
Presumably they've already coded to whatever the heck PlayStations use.
Yea, but the funny thing was about the semantic acrobatics around the word dropped.
The fact is indeed Apple dropped OpenGL from MacOS and as you said, the effort required from FD to move from OpenGL to Metal was not considered justified from a business perspective (they knew exactly how many Apple customers they got - and those customers could be playing the PC version anyway)
And FD is moving forward.
JWE2 is DX12 only
And i would say that ED is moving in that direction too while still trying to maintain full compatibility to DX11 (the EDO client is improved in may ways compared to the EDH client)