The flip side of this is thinking you can replace a complicated but working system "in a weekend at most", convincing management with a prototype that's missing all the edge cases and most of the features, and unnecessarily rewriting everything until you end up back at the start. An engineer needs a few attempted rewrites under their belt to learn humility in the face of business rules.
Of course, sometimes you actually can rewrite it in a weekend.
I've dealt with this mindset almost daily, but replace weekend project with a small to medium (sometimes large) project.
when they fail, they do not unfortunaly learn humility and do not end up back at the start (jobs on the line).
but instead massively descope the project and add a layer of 'shineyness' to the old working system. and now the company has to keep some of the old system in place, thus creating a service with two systems with two different type of technology. (pita for BAU run teams)
rinse and repeat every 5-10 years and the service now becomes a monsterous complex system
Of course, sometimes you actually can rewrite it in a weekend.