Can anyone explain why something like this is necessary on a Macbook, but when I use my airpods with my iPhone I seem to get high quality audio and microphone usage at the same time?
Are you sure? How often does your phone have the microphone active while simultaneously continuing to play audio? When the mic is active on a phone it almost always pauses music or video or whatever you're listening to. At that point it can switch modes and then switch back when you're done and go back to music.
On a PC (meaning the overall category of personal computers including Macs, not just a Wintel machine) there isn't that sort of integration. If you start a VoIP call with music going the music just keeps going, so the mode switch is obvious.
But maybe iOS just uses the built-in microphone more often to avoid having to switch away from (high quality) unidirectional audio on Bluetooth?
On the standards side, there's Bluetooth LE audio, which also offers very low latency, but that might actually require hardware changes (I believe there's reliance on some hardware layer changes).
However I can't really answer OP question. I am not sure how iPhone get a better sound quality if what OP is saying is true (I don't have an iPhone). What I know is that in Linux you can activate mSBC and this improves the quality a lot when using HFP profile, but it is still significantly worse than anything A2DP has to offer. I also think Android uses mSBC if available, but I am not completely sure.
[1]: https://en.wikipedia.org/wiki/List_of_Bluetooth_profiles