The interviewer wants to know you can make them. They can quickly figure that out in the interview.
Actually doing them teaches you how to make them, which will give you foundational knowledge you'll take with you into more complex endeavours. And it will show, I can tell if you actually understand why you built the more complex thing the way you did. If you just cargo-culted a bunch of patterns together in an effort to seem more competent than you are, a lack of fundamentals will show during interviewing.
I don't mean university course fundamentals, I mean pragmatic software fundamentals you get from building stuff.
It isnt about the product, it's about the journey. If you choose not to learn how to do basic math because the calculator can do it for you, you are missing out on huge swaths of understanding of math.
