Why don't amplifier Companies use high end fuses?

My equipment - Raven Integrated Reflection MK2 tube amp 58wpc. / Lumin A-1 DAC Streamer / Synology NAS / Isotex Aquarius Power Conditioner / Furutech Rhodium Plug / Sonus Faber Amati Homage Tradition speakers.  

I have read thousands of comments on upgraded fuses improving the performance of sound.  I am very open minded but not sold either way.  So, the question I have is....if fuses were so important, than why don't Amplifier companies all install them as OEM equipment?  To me, if they are as good as people say, that would provide companies who use them a competitive advantage?  

Every High End Audio store I go to in Phoenix have told me it does not make a difference and is a waste of money.  For the record, I have fuses purchased at an automotive store for under $10 and I think my sound is awesome.  The Company that built my amp tested the Synergistic Fuses and he emphatically said there was no difference.  

If I were to try a fuse for fun, given my equipment, what would your recommendation be to try?