Lucky me, I’ve received some LAN certs, but are they not useless?

For example, my flights YYZ-LIM costs $820 in Base fare (sometimes less with a sale).
One needs two upgrade certificates and a minimum fare of $1150 USD to upgrade, so my flight does not qualify for upgrade.
The next fare class up is Base Plus costs $992 USD so it does not qualify for upgrade either.
Next fare class up is Flexible, it costs $1502 so upgradeable to Full Flexible, tourist seats not Business.
In order to upgrade to Business seats using my certs, I need to buy Full Flexible at $2870.
But Business costs $2589.
Why would anyone buy Full Flexible at $2870 and use 2 certs to upgrade to Business when Business costs $2589? In other words, it would cost me almost $300 more to use the upgrade certificates! What? Is there something I am not understanding here?