The pricing model very much impacts users, because it incentivizes higher app prices, as well as subscriptions over one-time purchases. Users certainly don’t like subscriptions (but Apple loves those).
Whether third parties support Apple Pay or not is completely orthogonal to that pricing model. I use Apple Pay on web sites that have nothing to do with apps or app stores.
I don’t think I’d click on an external link to go to the app website to pay for anything