[balladeer]

Negotiating hard or casually is a two way process - you can't "negotiate" alone. If the offer was made that means both sides were negotiating hard. So isn't is off why that offer wasn't made at an early stage when the company was ready to make that offer and they eventually did

This situation reeks of an endorsement of some sort which if I may crudely put as - "if a potentially employer is trying to screw you over financially, do not resist too much".

What do you check in an employee "for sure" when you hire that employee - their performance in the interview. And you do that "hard"! What does the employee know about you "for sure" before they join you (and in fact for a some time even after joining) - that is how much they are going to get paid. That's the only thing they are sure of and I'd sure want to negotiate for that hard.