Dave Chinner works for Red Hat, and XFS is the default FS on the most popular commercial Linux distro. Seems like winning.
If you mean, "why didn't it win earlier?" it's probably a combination of ext3 being good enough (particularly when multi-spindle, large partition environments were less common for Linux users), Reiser3 doing a great PR job (pity about the crappy filesystem...), and ext3 having better data integrity because Ted T'so didn't understand how his filesystem implementation worked (he fixed that with ext4).
If you mean, "why didn't it win earlier?" it's probably a combination of ext3 being good enough (particularly when multi-spindle, large partition environments were less common for Linux users), Reiser3 doing a great PR job (pity about the crappy filesystem...), and ext3 having better data integrity because Ted T'so didn't understand how his filesystem implementation worked (he fixed that with ext4).