Mac OS was a step in a different direction, however development was far less compelling for OSX than classic. Think C was far more enjoyable and created far smaller and less power hungry apps, which allowed for a greater range of possibilities on low powered chips.
Going to use alternatives like Haiku that can access many modern systems but on such low powered hardware shows what wastage we have.
I fail to see how this compares to iOS which runs on phones or even devices with 15 watts of tdp laptops.