Managers in IT SHOULD BE software engineers. They grow from typical coding job.
Problem we have today is - companies just hiring young people without engineering experience and call them managers. Well, I call such people just engineer's assistants who can "make you a tea". How you can manage people and processes you don't understand?
However, being a good manager means having passion and experience in couple of disciplines:
Managers in IT = software engineering + design thinking + social skills + business skills
To be responsible for product, one should be very good in both software engineering and design thinking. Engineering managers might have less design experience, while managers/art directors in design agencies might have less engineering experience. Nonetheless, social skills are the most important and understanding business also.
Yes, of course, developers may become good product managers, non-developers will need to additionally waste at least 2 years to get engineering experience. I, personally, for years, not working with any manager who has no solid experience in engineering.