Football is littered with examples of people who were top class players but lousy managers. Thinking just of English clubs, just off the top of my head, I can give you Bobby Charlton, Bobby Moore, Mark Lawrenson, Tony Adams, Alan Shearer, Stuart Pearce, Paul Ince etc Given some thought, I'd give plenty more.
Then look at the managers who were very average or mediocre players: Mourinho, Wenger, Klopp, Pulis, Allardyce but have had a long and successful career (the last two may not have won anything but they've managed a lot of clubs and generally done well)
Being a good player and a good manager are definitely not the same thing
Completely agree, but being good at both isnt impossible, especially these days when you're not alone in the job