Being a Founder doesn't imply one is a good manager. It just means we were around when the company was formed!
Sometimes Founders do grow into great managers — and sometimes they were great managers already. But the real question is: "Do Founders need to be good managers?"
Ideally, yes. But it's not a requirement.
In the formative years, when we only have a small team, we can usually get by without being great managers.
That's because the team is still small, and mostly operates in a flat "team" structure without a lot of management to be had. That's also why Founders often don't realize they are shitty managers until later on because they ran for so long in an unmanaged structure.