Haha, damn right. If you only know how to play music from tabs, and if you only know rhythm by "what matches the song" or "what sounds cool", you don't really know music. I started from a long classical piano background, for the first eight years of my life. I hated it, but I 100% understand the necessity of it. It was a completely solid foundation for me on sheet music, theory, etc. Overlapping with the last two years of piano, I started playing clarinet for my elementary school band, and that continued all the way through.. well.. school. I picked up how to play Oboe, Tenor Sax, Bass Clarinet, etc. all along the way from spending about a year on each. At the end of my piano career, I started learning my first guitar, the classical guitar. The classical guitar is still played with sheet music, and time signatures, all the good stuff. I went through the entire Suzuki Method the way I did for piano.

If I hadn't gotten that kind of base for guitar, I definitely couldn't have taught myself "cool" music as fast as I did on acoustic and electric guitars I borrowed from my friends.

Also, you have no idea how insanely awesome playing "Greensleeves" or "Bouree" on an electric guitar with a distortion pedal is. I don't see "cool" guitar players doing that! Or.. reading sheet in general.

I've never written anything worth playing though. I have the theory knowledge to analyze pieces, wheel of fifth, etc. etc. but the extent of what I've written are cool guitar riffs from ear. Which I forget.