As you have discovered, you can play guitar without using your pinkie, but doing so will limit you to a great extent and certain chord voicings cannot be played without using the pinkie. Therefore I would strongly encourage you to begin incorporating the use of your pinkie into your playing.
Can you play guitar with only 3 fingers?
Look for alternate voicings that can be played with only three fingers. If you can at least mute a string or two with your first finger then that will help a lot. Especially in an ensemble of any kind, you can easily get away with chords that only use three strings without sounding too thin.
Do guitarists use their pinky?
THE PINKIE PREDICAMENT
But many guitarists stick to this tradition for most of their lives, playing only two-note power chords and pentatonic solos. It's no wonder the pinkie is notoriously weak for some players—it gets no love! In a nutshell, pinkie coordination and dexterity results from pinkie strengthening.