To be fair to the hardware manufacturers they are in a bit of a 'catch
22' situation with Linux because there are just so many distros and
all of them are being rapidly developed. Putting 'Compatible with
Linux' lays them open to being brought to task if certain distros or
updates break that compatibility in some way. However, ignoring Linux
altogether makes it look like their hardware will *only* work with
Windows / Mac ( there are plenty of hardware makers who used to ignore
Mac compatibility too until it went i386 and OSX arrived !! ).

The plus side in all this is that most modern Linux distros have made
huge improvements in hardware compatibility and most stuff will work
'out of the box' or with the help of the on-line community can be made
to work. It has to be said though that some hardware is never going to
work with Linux of any version - mostly due to the firmware being hard
coded to use Windows API's instead of doing the work itself ( lazy
programming or just cost cutting to keep the price down ??