Yes, I understand that Linux does have USB audio 1 support (either statically linked into the kernel or as a dynamically loaded driver, the latter being what OS/2 does).
I was just surprised that this does not come as a default. There are millions of users, including Linux users, that do not care and do not need to care what driver is used for what. But USB audio 1 is still dominant. It is much too early to drop USB audio1 support and you don't want the enduser to find out about it. For me, that is just a lousy user experience. And one of the reasons why I always was too lazy to move from Windows to Linux.