This is provocative but off-base in order to be so: why would we need to work backwards to determine architecture?

Similarly, "you can tell easily by just looking at the name of the model" -- that's an unfounded assertion. No, you can't. It's perfectly cromulent, accepted, and quite regular to have a fine-tuned model that has nothing in its name indicating what it was fine-tuned on. (we can observe the effects of this even if we aren't so familiar with domain enough to know this, i.e. Meta in Llama 4 making it a requirement to have it in the name)