Reasonable high caliber people don't need to be "managed". You can manage people working in the restaurant, make them a schedule, make sure they show up, etc. In a creative and intellectually challenging industry like SWE, why would you hire most bright people to pay them lots of money and then think they require continuous "managing". They might need someone to report to and escalate when need arises but that should be very lightweight.
Generally managers are used for handling failure of culture and the cause of that failure at the same time. If you are running a shitty shop, full of crappy devs, who you want to pay crappily, then you need a manager for ~ every 8 people, to whip them and make sure they are doing their jobs, and get fired if they don't.