Having flexible players is great but you can sometimes trick yourself into thinking you have more cover than you actually do. It's all good and well saying Wirtz and Szoboszlai can cover the front 3 but they're options for the midfield first and foremost. Likewise we'll have people saying Frimpong can cover Salah and it's alright because Gomez can cover RB but Gomez is currently our only backup CB. There's a bare minimum squad size you need, even accounting for utility players.Wirtz and Szoboszlai as well, surely? Admittedly they're each 50% midfielder 50% forward, but between them you get the one forward we're "missing".
Last season we had 12 senior players for the front 6 positions. With it being a strong possibility that all of Nunez, Chiesa and Elloitt leave, we'd be down to just 9 players for those 6 positions and in Salah, one of those is going to be away from the busiest 6 weeks of the season. Maybe you don't need 12 players but (particularly due to afcon) imo you need 11.