Earlier quoted context omitted.
I agree with you based on who is bringing the money to the table, but in most cases, the seller has signed a contract with the listing agent stating the fee structure for the deal before you made an offer on the house. The seller has obligated themselves to that structure, so you're not saving money by doing it yourself. I found our house entirely myself, but brought in an agent on "my" side with whom I'd negotiated…
Is there a reason you didn't do the deal without an agent and specify in your offer that you wanted the entire 3 points rebated back to you (which is kind of silly accounting, but whatever)? Certainly this would have been possible.
IOW, I don't think it would have been possible, as it wouldn't have been possible in my listing contract. If I thought it was possible, I'd definitely have gone that route (since 300 >> 75).
TBH, "my" agent added extremely little (it was her first closing) and may not have even been a net positive towards getting the deal to happen.
Edit: This was an existing house, not new construction.