It might be true because of the limited time NT coaches have to work with their rosters, but from a talent perspective, I don't see why you couldn't play all 5 at once. Silva & Fernandes creating for a front three of Jota, Felix & skinny-Ronaldo, seems like it would be terrifying to face if they were properly supported...which portugal has the talent to provide...and got comfortable playing together in a free-flowing attack.
The biggest tactical issue that I see with that would be that your fullbacks would need to be used more conservatively to compensate for the more aggressively aligned midfield like Pep has had to do in Manchester, and that's not exactly a crippling downside. So the question to me isn't can it work, but can your coach make it work with the time he has to get those guys to gel.