It most definitely is not, hasn't been for a while now.
I.e. when dealing with hosted models of the large providers, you are not interacting with a big bag of floats. You are interacting with an API/UI that presents an unholy web of software components, some of which may be large or small bags of floats, as if they were a big bag of floats.
Even with local models, you have dozens of parameters you can tune for inference these days, all of which affect quality of output in some way or another. And that doesn't touch load balancing, A/B testing, shunting token burners ("Hi chat, how are you?"), protecting user from themselves (refusing to answer "bad" queries, stopping "bad" responses), protecting user from third parties ("prompt injection" mitigations), protecting the model from self-pwning itself when calling tools, then the tools themselves, their prompts, the stack of system prompts used by the vendor, etc.
There's a lot of things to tune there, and just as many reasons to do it.