a. Thats your opinion.
b. Oasis made guitar music popular again and bands such as Coldplay and Kasabian have stated that Oasis influenced them.
Oasis got me into music, because of them I learned how to play the guitar and started to listen to other bands such as The Who, The Beatles, Led Zeppelin, The Kinks etc.
You only need to know 4 chords to play most of Oasis stuff anyway ! The more intricate stuff was nicked off the Beatles. A child could play most Oasis songs after just a couple of lessons ! A truly unoriginal band who hoodwinked a nation of non musical people !
