An orchestra has multiple people playing the same part. To do this out of necessity is completely foreign to me. I play guitar. If I need to be louder, I turn up the amp and bounce sound waves across the Schuylkill River (which I’ve done).
Since I can play a passage by myself at a volume appropriate for any venue (run me through the PA at the Rose Bowl), I do not need another guitarist to double my part. This puts me at the disadvantage that if I screw up, it’s all on me and everyone will notice. (This relates to my first rule of performing music: don’t make mistakes.) The advantage is that I can improvise and adjust the material as I deem appropriate for the particular piece and performance. There is one particular riff I’ve written that I’ve probably never played the same way twice; I add muted strings and play with syncopation when I feel like it. Right now, it’s just a riff. I’ve never tried to write a song around it, and I’m not sure how I could. I really don’t know how I could even get the bass guitar to play synchronized with me.
Why do you think that orchestras still simply double-up on the same lines rather than having one violin (for instance) that is played through a PA system? Tradition? (This is the part where my grandma would sing “TRADITION!” like in Fiddler on the Roof.) Do amplified violins sound goofy? I find it hard to believe that the latter is true when guitar tones (among other instruments) can be faithfully reproduced.