Why do guitarists make mode scales by flatting and sharping the notes?

Why is it commonly taught that guitar modes are made by altering major scale patterns? The idea is to think of everything as Ionian mode and instead of shifting to different degrees in the scale to create modes you should rebuild the scale and pattern completely.
For example, if a song is in A Dorian you could just play chords and patterns from the G major scale and focus on the second scale degree, A (the ii chord Am). Or you could use an A major scale, flat the 3rd and 7th, and then rebuild the scale pattern and chords. But guess what? Both methods give you the exact same thing!
I take the easy road - the first one. Altering everything is too much work, confusing and unnecessary. Also, it causes you to miss the fact that all modes are derived from the same patterns and chords. It's so much easier to think and play one set of scale patterns and chords for everything. That's what I teach and that's why my customers send me emails all the time about how they finally understand modal scales and successfully play modal music.
Guitar modes are taught in Fretboard Theory Chapter 8 and also the Guitar Modes - The Modal Scales of Popular Music DVD. http://Guitar-Music-Theory.com
Play Until Yer Fingers Bleed!
Mr. Desi Serna
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