Sometimes what it takes to get a feature is someone who’s motivated and capable of adding it with some help. You can see the rejoicing about the offer of that feature in Real-time backup. There are many other demands with not enough volunteers to get everything desired (including reliability and performance) as fast as wished.
Implemented backup based on changes recorded in NTFS USN journal #3184 shows the contribution of USN, while back in the forum thread there was some talk of Linux and Mac. Basically, still seem to need a volunteer. Feel free to send someone to that thread if you know anyone. There’s even an offer of guidance on the code.