Greg KH's comment about not letting yourself be limited today by the needs of commercial users of old kernels is a good one [1]. That would be a tail wagging the dog situation, where newer APIs can't improve beyond the support that's available in old kernels. If that were the constraint, then improvements which rely on available toolchains would have to wait years for those toolchains to read wide enough distribution to users with slow adoption schedules for new kernels before you could even think of building on those toolchains.

[1]: https://lwn.net/ml/all/2024092614-fossil-bagful-1d59@gregkh/