Why Yahoo! has never created a messenger version for Linux?

Yahoo! has created different versions of their messenger for both Windows and Mac operating systems, and for mobiles (iPhone, Blackberry, etc), but they have never launched an official version for Linux. And I can't understand why. If they worked for so many versions (for all operating systems), how hard would it be for them to crate one more, for Linux?

There are available many applications capable of connecting with Yahoo! (such as Pidgin or Empathy internet messengers, and a very complex dedicated application, named GYachE), but a proprietary messenger application would be well-welcomed. This can avoid from repeating the problem that millions of Linux users occurred just after Yahoo! updated the way users were authenticated on their servers (for Yahoo! Messenger 10). That made their servers to refuse almost any trial to connect from Linux operating systems. The problem was fixed, but that took some time.... And, on an official version, any functionality that Yahoo! can offer should work normally.

I really can't understand why they didn't made any version for Linux. Probably, they don't really care about users.