Because even if you're familiar with all the tech we use, you're not going to be familiar with the business domain, our cobbled-together solution on top of the tech stack, and the tens or hundreds of thousands of lines of code we nurtured over the past N years.

How you handle unfamiliar stuff is critical when evaluating an engineer. That's like the whole job.

Unless your goal is to churn out copycat CRUD apps and marketing pages your whole life. Then carry on :)