It didn't need to. The SD standards mandate support for FAT 12/16 (<2GB), FAT32 (<32GB) and exFAT (<2TB). A microSD card >32GB by definition has an exFAT file system, or else it's not a microSD card. In other words: If you claim support for microSD>32GB, you must support exFAT.

Claiming support for microSD>32GB without exFAT is like selling audio CD players that don't support compact disc digital audio according to the Red Book. You might be able to convince a few constomers that it's a perfectly normal thing to burn ogg vorbis files to a CD ROM and that this is like all audio CD players should work... but most consumers will feel betrayed, and they're right. The name "audio CD" implies a certain technical standard, and when you buy such a device, you never see "complies to the Red Book" written anywhere on the price tag. Still, you can safely assume they do follow this standard. It's the same with SD cards above 32GB and exFAT.