Stones can be caused by a lot of things. pH imbalances in that area, diet, etc. If she has trouble going, and has blood in the urine, it may very well be blockage.
That said:
And what do I say when the vet probably recommends some crappy Prescription Diet kibble.
I wouldn't sell the 'crappy Prescription Diet' so short. Sure it's shitty maintenance food but when formulated for a specific reason, it does do the job. We had a client who had the same view as you do and she refused to feed her cat u/d. Well 2 weeks later cat is back in to vets office
again with blockage
again and we got to do surgery and flush the stones out
again, which made the client pay $400
again just because she wouldn't give the cat u/d for the time period we specified. After that second surgery she complied and boom, stones didn't reform. Once the urine pH got back to normal to where it could dissolve the fragments, she was able to go back to her normal food. But pH isn't always the problem as there's a remarkable amount of crystals that can be found in urine, most of which have differing causes.
Also do your vet a favor and when you take her out in the morning, try to capture some of the pee in a cup or what have you. The vet's going to want to do a urinalysis and if there's nothing in there, well not much can be done.
And wouldn't an increase in drinking be a sign of a kidney problem? She isn't drinking any more than normal.
Depends on the problem that the kidney is having. If it's not able to dilute the urine enough, then the body will want water. If it's just blocked up, then the body will remain in balance/demand less since it's not expelling as much.