[dbetteridge]

You can, no-one is going to leap out of the bushes and mug you for doing so.

That said, you lose some of the advantages that come with modern tooling and frameworks such as easily breaking things down into components, using the latest language features before browsers ship them (I'm looking at you mobile safari) and handling things like minification, tree-shaking etc.

BUT that is OK, if you are happy with the tradeoff.