I buy a new team every season, it's far easier to get a 30 yo 5* than it is a 19 yo 5* on the transfer market.
And, since the introduction of the 'sell now' button' ' there's no problem clearing the same players out on the last day. And I win things every season against teams full of young players who have no doubt need a bidding war to sign each one.
That's enough evidence for me.