I agree. If a buyer wants to offer more, that is their prerogative and nothing unethical or immoral with that practice. On the seller side, also up to them by what parameters they judge who to sell to, person with best ratings, person they know, person offering the most, person who replies first, person in greatest need, person who replies last, person they feel most secure in selling to, person who it is going to be easiest to get the item to. There is no required protocol so totally up to the seller. Anyone who has problems playing by open rules, should just not play. No call for pointing judgemental fingers based on personal per-conceived notions.
Very nicely explained, Bill!
The offering seller is presumptively committed to honoring his proposal, but not to any specific buyer, until both mutually-agree. That's why we have things like ratings, history, location, experience, earnestness, comfort percolating in the background. First response generally carries a lot of weight... but is not the only or even overriding consideration. 90+% of the time, deals here are friendly, direct, quick and agreeable.
But there's the few % habitual tire-kickers wheeler-dealers who we experienced buyers and sellers learn to avoid. One guy, on a minor $50 bargain item I was selling peppered me with interminable questions, and then went ballistic when I stopped responding to more and more questions. I deleted his messages and swore (to myself) that I would never communicate with him again, on this or any future deals. Someone else happily got the item; I even threw in extras gratis because he was considerate. I've casually discussed this sorta dynamic with some commercial vendors and learned the same thing. We have our secret lists... and they also have theirs! If you earn yourself a reputation as disagreeable, might explain why the communication channels seem to dry up and go dark... and yet others seem to be having no issues. Tom