Many guitarists are adamant that the only way to learn guitar is by learning to read sheet music. Some even go so far as to say that if all guitar tab was removed from the world the level of guitar playing would be much higher. The main objection to that idea is that many famous guitar players never learnt to read sheet music. Some even have trouble with tab. Eric Clapton, Jimi Hendrix, Tommy Emmanuel and Jeff Beck are shining examples. Of course, all these guitarists were following their own idiosyncratic ways of expressing themselves through the guitar rather than learning a broad range of music but there are still those who are thinking of a whole world of music that is closed to people who have not learnt to read notation. What would possibly be raised if tab were eliminated would be the level of communication between guitarists because we would all be speaking the same language.
But it is highly unlikely that guitar players who have more of an instinctive approach to the guitar will ever take the trouble to learn theory and standard music notation. At the same time the people who have made the effort to learn to read music will continue to feel that they have a greater understanding of the guitar and the ability to learn new music faster than guitarists who do not have a background of theory at their fingertips.
You could say that the bottom line is what works for the individual. If you can play guitar but can’t read music, does that make you an inferior guitarist? A weakness with learning from tabs is that timing and rhythm can’t be learnt from tabs but some people write tabs incorporating the elements of sheet music notation that show note values and timing, and this kind of notation is very easy to learn.
There are those guitar players who see sheet music notation as a language that was invented by keyboard players and is not very well suited to the guitar. It should be noted that without learning musical theory as well, learning to read music is just a part of the language of music and is not a great deal more useful than tabs. Also the amount of music theory a guitarist learns is in proportion to his interest in music in general but will not necessarily make him a better guitar player than a guy who doesn’t read music.
It has often been pointed out by guitar players who play in an open or alternate tuning that if you are used to reading and playing music in standard tuning you might find it very difficult to sight read a piece written in an alternate tuning using standard musical notation. If this is true it would suggest that reading standard music is not the key to universal understanding of the guitar.