Some of these teams have wingers that don't exactly put in challenges, I agree. But they cover (like literally just occupy space) the wide areas so the CMs can all stay compact in the centre of the pitch. In a 4-3-1-2, how do you help De Sciglio defend? You have to bring a CM all the way out wide? It's so hard. That's why it's uncommon.
Then the issue of when the CAM goes into the box. It helps to be Vidal who goes for a header and then sprints back beside Pirlo. Just think how we got murdered by Ajax with 2 banks of four but then eliminate even one more player so it's a bank of 3 and a bank of 4? There's no way IMO.
This is not even talking about the attack, which is so much harder. Again, imagine De Sciglio with the ball and how does he pass it out of our 3rd? Well it's going to have to be a striker that drifts all the way wide to receive the ball, in which case he's playing as a winger anyway! So put a winger there!
Wingers
Edit: Also really hard to press the opponent. What happens when they pass to their fullback? A striker or CM has to go there. So just put a winger, e fatta.
^^^ So if you pass to the fullback, either a CM or a ST has to act as a winger, so just put a winger. Preferably Hazard.