No, I haven't suggested that at all. You haven't read carefully enough.
What I've suggested is Robertson is able to command a fee (whether it's paid up-front or added to wages or split between the two). The reason is that Robertson is a substitute, an alternative, for players who are under contract. The key issue is what he brings vs the total cost of "ownership". Once he signs he is also under contract and would command a transfer fee should he leave (this being the flipside of his out-of-contract fee on signing/paid through wages).
So to repeat my earlier point, a player like Robertson is not "free" as some on this thread are assuming. We pay effectively a transfer fee to Robertson via the above mechanism.
It makes perfect economic sense, and what's more, happens.