The point is that a computer will just be another thing for them to learn, not a replacement for other tools they’ve been using for tens of years. Therefore, the computer does not need to look like those other tools in order to make sense to them.
The fact that the people learning it will be younger is not a reason to make it harder for them to learn. The computer doesn't need to look like other items out there in the world, but it sure is helpful, even if only so you have a reference to explain things from, and so that the iconography is somewhat consistent.
Have you tried teaching kids (or just people in general) abstract concepts? Even maths is taught to kids in terms real world items and reasonable actions you can perform with them (you have 5 friends and 25 cookies, how many cookies does it friend get if you give each friend the same number cookies?).
The more you can ground what you're teaching in real world terms, the easier it is to teach. And in the moments where it does deviate from real world conditions, that's where it becomes harder to learn, since now you have to remember exceptions in behaviour compared to what you already know.