Right I get all that, but it doesn't make sense...
Stay with me a bit..

There's a good chance that like me, a lot of peeps will have version 7.4 Infinite as well as 8.4, do we agree??

Now I can upgrade from 7.4 to 8.5 at the upgrade price because I still have 7.4 but I can't upgrade from 8.4 without effectively paying more than if I upgrade from 7.4.....!!
Makes no sense, why not give the 7.4 upgrade price for 8.4 too???

Injustice will be avenged.
Cofiwch Dryweryn.