Thanks very much for all the replies. Very interesting!
Seems absolutely idiotic that the Standby List in the app shows unassigned seats as opposed to inventory. That does nobody on standby any good and is essentially a useless number which could be gleaned from the seatmap if anybody cared...
It's the right number to be shown. Knowing how many seats DL is selling is useless. You want to know how many actual seats are available. You can't get on the plane without a seat assigned. Thus you know exactly how many seats are left to be given out.
not sure what use knowing the number of tickets DL is willing to sell would be.