I know Azrael who is a host on this site put the guitar down for a year or something because he wasnt getting any better. He then was introduced to a guitar teacher who made him pick up the guitar again and improved so much and now is a really good guitarist.
By virtue of their electrical properties, tubes generate a special waveform when they're saturated, which is why tube engineering has tremendous tonal advantages over solid state or DSP solutions, particularly for crunch and lead sounds. Tubes enter the saturation zone gradually or softly, which lends tube-driven tone its trademark yet totally unique character.