Not dismissing the concern but perhaps like the frog in the pot, just keep turning up the heat,
but this has not gone unnoticed on FT, with the classic
"Upgrade PlusPoints (was GPUs & RPUs) are useless nowadays"

and many others pre-COVID threads
A Comprehensive Look at Domestic First Class Monetization (FCM) on United

UA Upsell Offers to Business/First/PP at Purchase and Day of Departure (TOD)

Are paid upgrades getting cheaper?

Wow - selling the upgrades at the gate so explicitly.

yet most are still here

and we have our annual PlusPoints Polaris flight upgrade SUCCESS 2021 so some upgrades still happen