In my home state at least, a sellers' agent is legally and professionally obligated to present all valid offers received to the sellers. Failure to do so can result in legal liability, fines, loss of license etc.
If your state is similar, then if you had made an offer by any means, like via the agent's voicemail and the agent didn't tell the seller about it, then you would have had cause for legal action.
I never made an offer. I was simply trying to see the house without an agent of my own. The house in question was near where I was renting and had been on the market over a week without an open house. It went to pending a week or two later. The seller's agent never got back to me at all.
It's funny you say that about legality though - some of my relatives recently put in a low-ball offer on a place in AZ. The seller's agent called them back, said it was insulting, and would not be even showing it to the owners. The house had been on the market for months. I wonder if that was legal.
If a market is hot then bidding is necessarily going to be more competitive and sellers are going to be less accommodating. It's not unusual for buyers to make an offer site unseen in a hot market. So if you have the cash and you really want the house, I suggest you check out the rules in your state and next time try making an offer by any necessary means.
If your state is similar, then if you had made an offer by any means, like via the agent's voicemail and the agent didn't tell the seller about it, then you would have had cause for legal action.