Also ..... all dist/OD pedals have their own sound ...... there's nothing wrong with liking that sound and just straight into an amp isn't the only way to get a good distortion.
For Greg it is because that's a key element to his sound. What is gonna be key to your sound might be different.
Yup. I just prefer the simple raw tone of guitar + amp. My tonal requirements are fairly basic. You do what you gotta do to get the sound you want. That might mean a different guitar or amp, or just adding a pedal or two.