Problem purchasing iPhone 17 with T-Mobile prepaid service

I spent most of this morning trying to purchase an iPhone 17 on the presale. I intended to use a trade-in value of $170 from my existing iPhone and finance the rest on my Apple Card for free. Apparently because I have a T-Mobile prepaid service instead of a contractual postpaid service, I'm not able to do that. I cannot understand the rationale with blocking an iPhone 17 purchase with trade-in value and using the Apple Card financing simply because of the level of T-Mobile service. Has anyone else run into this problem? It feels like a coercive effort to push people into higher end T-Mobile contracts. I've been buying iPhones in this manner for years without any such problems.