I got this interesting question the other day from a singer/songwriter. "As an artist, do I have to play an instrument?"
Let me start by saying that the voice is an instrument too. Don't use this as an argument to not have to learn how to play guitar or piano, but working on your voice is as important as working on any other instrument.
Before you decided to pick up a guitar, ask yourself how much you have invested in your voice. Do you warm up, do you practice? Your voice is where your artistry starts first. its the most recognizable part of you when they hear your music come through their speakers.
As an artist it's so important to know what it is that you want to say, what do you want to write about, what do you want your audience to know about you? When you walk into a writing room it's important to have your stories ready to talk about, your melodies on hand that represent you that are so uniquely you. If you walk into my writing room, you don't need to bring a guitar if you don't know how to play, but I do need you to walk in with your ideas, your identity, your words so that I can be the best co-writer for you to write what's on your mind.
As a producer I love it when the artist is involved with their sound and is able to express what they like and don't like. To be honest, if they play an instrument it makes it easier for me to understand what they are looking for, since they can play a part, talk about chords and chord charts. Again, you don't NEED to play an instrument, but if anything, spend some time understanding basic music theory, chord structures etc. so you can talk to me and to your band members and explain what it is that you would like to hear.
Your personal growth
I believe that knowledge is power, so eventually, in order to keep growing, I would highly recommend you picking up an instrument, start looking for some youtube tutorials and give it a go.You don't have to aim to be the best at it, but it will keep you on your toes and it might inspire you to write something new and fresh.
So, do you HAVE to learn to play an instrument? No, not at all, but you might want to if you want to turn this into a long lasting and thriving career!