On computers per se, yes. But it is very widely used on peripheral and quasi-computer devices. The obvious example is digital cameras: every digital camera made today (so far as I know) uses FAT and/or FAT32.
But hoolie doolie, who are they kidding? It's not like there is anything particularly clever about FAT. It's a very, very simple and obvious way of formating a drive with no particular technical merit. The only advantage FAT has over any of a milion other simple brute-force file systems is that it is practically universal. This, in other words, is a very, very clear case of Microsoft abusing monopoly power. This is as ugly and as unethical and probably as illegal as any of the bad things they have done in the past.