Only in that you've missed Bobbsy's point. The point is, everything wears out or breaks down, and software is continually transitioning. If you don't upgrade periodically (and that may be every couple years, or every couple months) you will have a HUGE learning curve when you DO (and you will) break down. It can be hugely frustrating to go from Cubase 3 to Cubase 8 or Reason 4 to Reason 7.1. Those are huge jumps and lots of new stuff to learn. Hardware and OS is a completely different story. If you're running a Windows 98 machine for the last 10 years, and your hard drive goes down, you will have a MAJOR task on your hands to get it back where it was. A 10 year old hard drive may or may not still exist on the market, and finding a useable version of Win98, all your software, and all your plug-ins may be near to impossible.
You are correct in assuming the old "if it ain't broke, don't fix it" adage still is true. If you get good sound from your system, go ahead on! But you may have a problem fixing it when it breaks.