Theory

[Lindsey]

I’m honestly convinced every professional guitar player who say they don’t know theory is lying. They probably know at least the very basics.
Why do you need theory you ask?
Well it’s for communication purposes(communicating music with people with limited music theory knowledge is honestly pretty close to a nightmare because you usually have to give them a speed course on basic music theory while you’re at it), It also makes writing a song a bit easier(cadences and stuff like that), It also provides a backbone you can fall back upon, it helps soloing(like finding arpeggios, notes, scales that work), it’s easier to study other songs or just musicians and take that inspiration, you can find substitution for chords(this works for rhythm and soloing)

"I’m honestly convinced every professional guitar player who say they don’t know theory is lying. They probably know at least the very basics."

I feel the same way about that. They probably mean that they did not learn it from books, or don't know all the official names.
But knowing theory isn't just remembering something you once read, it's understanding music and those professionals understand it.

(And looking into theory helps)

 

[Calvin Phillips]

Once you learn the patterns you know the theory. I think that's the easy part too. Once you figure out the patterns everything comes together. Some people just choose to take the long route. I wish I didnt originally take that route myself.

 

[Bartosz Tkaczyk]

It's probably not necessary but it will help you understand many things. That's my opinion.