Linear regression is machine learning. At their core neural networks are just repeated linear regression + a non-linearity arranged in interesting ways. The key

Linear regression is machine learning. At their core neural networks are just repeated linear regression + a non-linearity arranged in interesting ways. The key is that they can be trained to fit data using some optimization protocol (e.g. gradient descent). Just because linear regression has a closed form solution and is conceptually simple doesn't mean anything here.