It starts mattering more for consumer software when you reach mass scale. Somewhat hard-to-find bugs at the scale of hundreds of millions of users (like a social media company), turn into bugs faced by hundreds of thousands of users.
But at that scale (in my experience), QA is up front and center and is typically a core pillar of engineering orgs.
My counter-point to this is that babies are born with a sort of basic pre-trained LLM. Humans are born with our analogical weights & biases in our brains partly optimized to learn language, math, etc. Before pre-training an LLM, the weights & biases of their analogical brain are initialized with random values. Training on the internet can IMO be seen as a kind of "pre-training"