An Engineer's Job is not to Write Code
An engineer's job is to deliver working software.
A delivery driver's job is not to drive a truck, it's to deliver packages. Driving the truck is a means to an end.
When a dev team starts to grow, it's unavoidable that you'll have to implement some procedural overhead. When this happens, some developers will grumble that they don't have as much time to "do their jobs"—meaning to write code.
You wouldn't judge a delivery driver's performance by the number of hours spent behind the wheel. A high-performing engineering team delivers features, not lines of code. With every additional team member you add, the complexity of coordinating their efforts grows exponentially. For engineers who were used to the lone-wolf way of life, this coordinating effort can feel like a distraction.
This is why your team needs to be united in their goal to ship features reliably and consistently. To unite them behind this goal, you need to track—as a team—features delivered and milestones met. This way developers can focus on real progress, even when they're forced to talk to each other instead of "doing their jobs."