Relevant knowhow allows you to cut the right corners.

You'll have the gut feel of which corners are safe to cut now, because you know you can un-cut them later.

Cutting them now allows you to quickly validate an idea is viable as a prototype before investing the time to harden it into a production system.

But you have to know that you didn't accidentally back yourself into a corner with that shortcut.

People without relevant knowhow in a system won't even realize they're taking shortcuts, let alone whether they're good shortcuts.