OP, did you skip over the first part of my post?
As I said, sometimes “make an offer” will appear without the seller’s knowledge or permission. Your lambasting such sellers for enabling make an offer is illogical.
Even if a seller enabled it himself/herself, it’s not incumbent on that seller to accept your offer. To label such sellers as inadequate is unjustifiable. I’m not saying this as a “bitter” seller as I’m neither bitter over “20% off” offers nor am I a seller.
Sellers may enable “make an offer” for specific purchasing situations — multiple item discounts, repeat customers, and so on. In other situations, because it doesn’t suit their selling model, they may only be able or willing to accept a small discount offer.
You’re perfectly entitled to make what I (and many others) consider lowball offers. Sellers are perfectly entitled to reject such offers and even to block you. That’s how it is. You may not need to think of ways to block sellers who have rejected your offers in the past, as it’s at least possible you’ll be blocked from buying from them, which solves that issue.
If you do want to keep a record of sellers from whom you don’t want to buy, I realise it’s tedious creating saved searches with specific exclusions, but that is the only option for you, I think. Your buying pattern clearly favours the sort of items that have a sufficient margin to let the sellers give you that 20% discount. That being the case, there’s no further suggestion I have, as my buying pattern is different.
Your buying is up to you and what you offer is up to you. The other responders on this thread are in essence pointing out that the opposite is true as well - that sellers’ selling and what offers they accept is up to them. I don’t think you should be labelled as an inadequate buyer, so why are you labelling sellers who can’t or won’t give you a substantial discount as inadequate? That’s what has me puzzled.
