The short answer is "No". The long answer is "No, absolutely not, painting by numbers is NOT cheating. Give two people the same paint by number and see what happens."
Paint by Numbers are a great way to learn how to paint, and can give the most inexperienced artist a place to start, but when it comes down to it, you can tell the difference between artists, even when they do a paint by number kit. If you do a paint by number kit and follow the instructions, you will have a beautiful end product, but if you start applying the most advanced painting techniques you'll have a masterpiece.
There are many different painting techniques. The most experienced painters can blend to make a very realistic end painting. The artist may prefer soft edges or hard edges. You may want to use dry bristles or wet bristles to give the painting a different effect. Different strokes will produce different textures and can drastically change how the kit looks. Even the simplest thing like the consistency of the paint is something that separates an amateur artist from a professional--you can't mess up, but with practice you can get much better!
Paint by Numbers give a good starting point for anyone to make a work of art and dip their brush [toe] in acrylic painting. If you've never tried before, start with paint by numbers!
We've had to field this question on our website, emails, in chats, on our blogs, on our Facebook page, in our Facebook group, and in real life and finally wanted to put it to rest. If you agree or disagree feel free to leave a comment below!