I don't think there's anything inherently wrong with makeup at any age. The only thing that worries me about makeup at a young age is what is in there is a lot of toxic ingredients in most mass market makeup products that can have pretty disastrous effects on young children if used often enough, especially young boys. I myself gave up make up almost entirely a few years ago when my grandmother died of cancer and I learned makeup is often full of carcinogen. It has been a huge time and money saver in my day to day life.
I think the true answer here is to try and normalize acne and skin problems. We can definitely do it, vitiligo has become celebrated it used to shameful not even twenty years ago. It isn't fair that kids should spend a significant amount of what little money they have access to to pay for makeup products that can put them in harm's way.