Well, yes, sort of. But with respect to the FFP evolution, perhaps a bit of history will be good for the "younger than me" crowd.

When the upgrades started as a perk, F was not generally going out full, and the perk wasn't unlimited upgrades. The status flyers received upgrade coupons (i.e., for UA it was 500 mile certificates) which you could combine for your domestic (only) trips. You could also buy more if you ran out. Top tier rarely ran out, lower tiers had to decide whether it was worth the extra dough to purchase more certificates. F travel could be exponentially more expensive than the cheapest Y, and the Y experience wasn't half bad back then. F / J didn't have a panoply of fares, from full to highly restricted. It was full or nothing. So, the business model at the time was giving away seats that would otherwise go empty as a perk, even if the perk could cost you $ from time to time.

Then one by one, the airlines started with the "unlimited domestic upgrades," which is silly because it provides for the illusion of a benefit that only the rarefied few will ever benefit. Standby lists of 50 to 100+ aren't uncommon. F / J fares came down (not the unrestricted ones, but ones with refund/change restrictions). More people started buying the seats. Less UG availability. Then airlines introduced upselling - more people paying at least something more for the seats.

As an early 90's UA 2P, my domestic UG % was around 50%. As an early 90's UA 1P my % was about 75%. As a mid-90s onward to early 2000s UA 1K, my rate was probably 95% - and this is SFO-based.

The underlying business model of the upgrade programs don't even vaguely resemble their initial configurations, and I think that would be the case even if we still had a few more major players that weren't acquired in the meantime.