When you have small domain, any progress can be seen as big. Now when you have many millions of lines in linux kernel, half a million new lines is "oh, just another module". The same with whole foss domain. It's so big now that progress is seen as slow. Comparing Blender now to Blender in 2014 will show you how big progress we still make, just as an example.

Another module in linux isn’t half a million of lines. A whole new class of hardware with all the drivers may be.