As a 'web developer' you can pick your area of expertise. Nothing says that as a front end developer I can't learn Java and become full stack or backend. People can pivot within the world of web development.

If I find I am not standing out as a Python developer I could very well decide to learn either Vue or Java to stand out. Either language is still within the world of web development and would key in with existing skills and knowledge. What wouldn't make sense would be apprenticing in carpentry, that's not going to help you stand out as a web developer.