I speak from my own diymod experience. I have tried many many different caps from 4.7uf to 3,000,000 uf and some difference made is big (hate to use the words day and night). It makes me to appreciate the iems and amps I have. No iems or amps will clean the dust created by the circuit, period. Even the lod's make quite difference immediately before amping. I am glad I can experiment and hear all these differences myself.
If you don't mind me saying so, I think the example you provided above is rather inapplicable. I don't mean to insult your DIY skills in particular, however if a DIYer were to use components of the wrong value altogther is building a poor product and doesn't know what he/she's doing.
The assumption is that a commercial business do actually know what they're doing and are using the right parts (or at least the right values at the very least, but maybe not the best quality components from a cost perspective).
I could be wrong but I believe up to a certain point of a product design, it can be deemed as "right" and "wrong" but beyond that point, is a matter of design style preferences, management of manufacturing costs (parts & labour), etc. And in commercial products I think the differences we hear are the latter preferences - and that's where the resulting variance can be deemed "minor" depending on the listener's ears.