I'm not sure the primary usage is to prevent the "FAT" tax. Sure, it could be useful on SD cards to replace exFAT. But I think the primary goal is to replace ext4 for eMMCs embedded in smartphones (and tablets, or any other smart device). This limitation could then make (a little bit) sense. With current technology we have 64GB eMMCs, with 128GB in the pipes. With capacity doubling every 2 years, it would take ~15 years to reach the filesystem limit. Let's hope that by then non volatile memory use will be pervasive.
The thing I don't understand, is why work isn't done to make btrfs fit this use case. It already has less write amplification than ext4 or xfs due to it's COW nature (I think Arnd Bergmann did some research on that). It would use the years of experience and higher performance of btrfs (vs a newly developed filesystem). It would also fit the Linux philosophy of running on anything from the tiniest devices to TOP500 computers.
Is it because btrfs as a high CPU overhead ? Consumes lots of disk space ? Or just because every btrfs developer is working on "big data" server-side use cases ?