Really though, they seem quite bright. But I like seeing younger people excelling like this because it means the tutorials, wikis, blogs, etc. that their "forefathers" wrote are doing "good" in the world.
Rapid feedback and short iteration cycles are often considered to be an important part of agile development. TDD suggests that you write a test first, and try to make that test the smallest increment that moves you forward. It feels to me that TDD is an application of the principles of rapid feedback and short iteration cycles on the level of code.
If you think using TDD improves the quality of your code, then it's also important for maintaining high code quality, since that enables some of the other agile practices, such as frequent releases.
I don't worry too much about whether a particular practice is agile or not. If you find TDD useful, then great! It's often included in conversations about agile development, but that doesn't mean you have to be doing agile development in order to use it.
Agile warns against building stuff you don't need. TDD means that test provide the justification for feature work. If your feature work isn't making a failing test past, you don't need that feature work. Obviously this assumes that your tests are justified (ideally there is a stack of tests leading all the way to the end user experiment), but that's much easier to get right than justifying untested feature work.
A previous company I was at worked this way and it was a dream. That said, it does require very selective screening processes and maturity from those you do hire.
However, it was the most happy / least stressed I've ever been in my life. I still get beers almost weekly with over half that team. This "strategy" really built comradery because we were always talking and discussing rather than leaving comments on some Jira ticket (which we did for async or when necessary).
I recently quit a job because I was the only one on the team "capable" (or that felt confident/comfortable) saying "No."
As a "devops" (loosely defined on our team) I felt my focus was uptime and error rates which sometimes is counter to new features (what managers want)...
Really though, they seem quite bright. But I like seeing younger people excelling like this because it means the tutorials, wikis, blogs, etc. that their "forefathers" wrote are doing "good" in the world.