I understand that logic, but riddle me this.
On Wednesday there were three seats together, available in the family stand. In that stand it is not permitted to buy any seats without at least one U16 in your party, so the seats put up must have come from a minimum of one junior. Yet you can only buy them at £35 each (full adult price), even if you want to go with two toddlers.
There was a line in the club's news item when the exchange was unveiled that said "Tickets listed on the ticket exchange will be sold at adult match ticket price." Given the general poor quality of the club's comms, I put it down to poor wording because, like you, it just doesn't make much sense for there to be odd tickets which could not be sold at a concession rate.
But, no, here's a single ticket in the Family Stand...