It’s a fair argument but, I think, rather idealistic. EtH is a pragmatist and first and foremost he wants to win - that means now, not when he’s got his perfect squad together.
It’s not about fundamentally different tactics, it’s about nuance, balance, small adjustments to improve the chance of victory. Playing a more defensive full back, from time to time, against a dangerous winger, is exactly the type of thing EtH would do. He’s played Fred as, more or less, a no10 before, purely as a tactical decision to suit the game. I think he would want a squad with options that allow him to alter the balance as circumstance demands. But, as you say, no two players are identical anyway.