Of course some people just have really bad voices and probably can’t but for those who aren’t is it possible? I’d much rather sing out melodies and lyrics rather than have an instrument and a robotic voice do it; its time consuming and usually doesn’t turn out so well T_T.
Some people really can not sing, and can not be taught. That said, if you can match a pitch and carry a basic tune you can learn to sing. You have to learn technique, breathing, posture, and exercise your vocal cords to expand your range and learn breath control and how to stay on pitch. It takes time, years really, and lots of practice and dedication (unless you are just gifted).