While I tend to agree, i still feel like i have to give some examples how it could go: So far I had 4 flights with QR this year, and on 2 i managed to get an upgrade. One was, I have to admit, on the very obscure DOH-CKG (that's Chongqing, not CGK, Jakarta) route, where it seems quite easy to get an upgrade. The other one was, however, on DOH-ZRH, with plenty of other people in the cabin (if memory serves me right more than 6, in a 787 none the less!). Upgrade was requested and granted about 2 weeks before the flight.

I guess if you're flexible, your best bet is to call the privilege club number of your country (or departing country) first, to check for availability. Then book it and immediately call again to get the upgrade (or request it online, but that usually takes 24 hours).