Comment by jchw
The entire point of the free software movement is to promote free software principles and software rights. What I think many Linux distributions would prefer is a model where companies who do benefit from selling software and hardware are funding them indirectly, so they can focus on continuing to promote free software in a more neutral way, without the pressures and potentially misaligned incentives that come from running a store front can bring.
There are distributions like elementary OS which are happy to sell you things with this model, though, but I just don't think it's surprising many distributions would actively prefer to not be in this position even if it leaves money on the table. This sort of principled approach is exactly why a lot of us really like Linux.
It's really unfortunate the term "free software" took off rather than e.g. "libre software", since it muddies discussions like this. The point of "free software" is not "you don't have to pay," it's that you have freedom in terms of what you do with the code running on your own machine. Selling free software is not incompatible with free software: it's free as in freedom, not as in free beer.