Not all pros are profficient with theory, but it really does help when working closely with other musicians and with transcribing your music. Knowing how the notes in a key relate to the chords in a song will allow you to add more variations to your music, and can save time trying to find something that fits.

I think a good understanding of theory is important when communicating ideas with other musicians, and when you want to be able to break down or play along with songs quickly. I think learning theory is important but that you should never feel like you are confined by it. Its not a rule but a guideline. Play what sounds good.

Its helpful but some of the most amazing guitarists dont know music theory

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Dont stop keep going-frank zappa Find what your good at and exaggerate it-steve vai

Another way to look at it.

You can get in a car and drive it and not know anything about the parts that make it work and in time you may be able to drive as well as any race car driver.

So lets say the car breaks down you pull off the side of the road open the hood and see stuff. You have no idea what any of the parts are or how they work together to make the car move. Even if there is a simple fix that will get you back on the road, you can't see it.

Whether you are driving a car or your fingers on a guitar neck, the more you know about anything you do, the better you will be in the long run.