Except it's the same problem for experimental papers. My thesis was based on a highly cited experimental study. My role was to "support" that paper with numerical simulations. And yet, at conferences, people would openly discuss if the original, highly cited paper, was fact or fiction.
The guy built/fabricated a device, and reported interesting measurements. Want to know if it's true? Build it yourself! Except when you do and get differing results, there will be quibbling over whether you built it properly. There are always details left out of the original paper that can be appealed to. The original author is king of the field, and people will simply ignore your contrarian findings.
For theoretical/numerical results, it is for sure valid to criticize assumptions. But in the longer time frame, the question shouldn't be "Are these assumptions valid?" but "Is there experimental evidence to support these calculations?" With a lot of the papers published (including mine), I can assure you that no one will ever be able to construct an experiment to (in)validate my results. And that was true for probably over half of the theoretical/numerical results in my field. We were all publishing things that most of us believed could never be connected meaningfully to the physical world. We're not talking string theory or high energy stuff - more like material properties.
The goal was to publish, and convince others. Not to understand reality. Hence, more like literature.