If a manager communicated with and listened to their team, but their team had written a web service with gaping security holes or disastrous data integrity practices because all their senior engineers were incompetent and/or were hired at a level that was above their ability, would that manager find out just from chatting with them?
I promise you that it's not guaranteed. You need to actually go looking through the code to find everything that's wrong.
Doesn't work, because the team won't always tell you of the issues that block them (normalization of deviance). Sometimes you need to find out yourself.
Some managers will do that. Most won’t. Given that, it’s easier to just tell them all to code.