Warning. I know little about playing an acoustic guitar and have never played an amplified or electric guitar. Furthermore, I sing mostly folk songs from Virginia. There are plenty of examples of folk singers who accompany themselves traditionally with some sort of musical instrument; e.g. Larry Older (fiddle NY) Frank Proffitt (Banjo NC) Jean Ritchie (dulcimer, KY) Rick Ward (fretless banjo, NC), and in the acknowledgements to the Mary Lomax Ballad Book, Art Rosenbaum mentions that while Mary no longer plays her guitar, the instrument was part of her traditional music background. I think in Virginia almost all folk singers sang there songs without accompaniment.
On the plus side, I have listened to Carlos Montoya practice the guitar in his home in Wainscott NY and every year I attend the International guitar festival at Radford University. Admittedly Covington Hall has incredibly good acoustics, but I still think I have heard what can be accomplished on a classical unamplified guitar. The right acoustic guitar in the right hands is like a one man orchestra.
I have a colleague who plays an amplified guitar and who makes the case that with amplification you can get better sustain and better reverberation than you can get on an acoustic guitar of the same quality and cost. If you go to you tube and enter schang1971 you can judge for yourself (go to the practice sessions and skip all the maths lectures) Part of the problem the amplified side has is that much amplified guitar music is played badly. At least if you listen to S. Chang you will hear well played amplified music. By the way look at the finger nails on his right hand (They are not bits of tennis-table balls glued on.)