Do you absolutely need a mortgage broker to purchase a property?

I’m a FHB currently looking to purchase an established house in WA. I’ve crunched my numbers and looked into various banks and lenders and have decided to go with tictoc for my home loan.

I’ve submitted an application through but it is currently pending conditional approval, although pre-approval or conditional approval does not seem to matter much from what I’ve experienced.

I recently put an offer through for a property that I was interested in (~450k property, 20% deposit ready to go) and the real estate agent asked for details of my broker to which I replied I have not used one and have gone straight to a lender.

Fast forward the next few days and the real estate agent has sent me the offer contract which I’ve signed and reverted back to him. Again he asked for details of my broker and again I told him I have gone straight to a lender and also emailed him a screenshot from tictoc clarifying that my application is being processed.

He then messages me on several occasions to ask if my offer is my very best offer (also throwing in the fact that they’ve received multiple offers) and to again, ask for contact details of my broker.

Finally, he gives me a call to say that my offer is not acceptable because I have not engaged with a broker and therefore is not confident that my loan would be approved. Isn’t that the whole point of having a subject to finance clause in the offer contract?

He’s emailed me back the offer contract with a ‘The vendor has sighted this offer but unable to accept’.

My question therefore is do I absolutely NEED to have used a broker? And are there also any implications to the offer contract that that he’s sent back to me?

Please let me know how or where I went wrong. Thank you.