I might be misunderstanding your point, but quantization can have a dramatic impact on the quality of the model's output.
For example, in diffusion, there are some models where a Q8 quant dramatically changes what you can achieve compared to fp16. (I'm thinking of the Wan video models.) The point I'm trying to make is that it's a noticeable model change, and can be make-or-break.
Of course, no one is debating that. What’s being debated is whether this is done after a model’s initial release, eg Anthropic will secretly change the new Opus model to perform worse but be more cost efficient in a few weeks.
For example, in diffusion, there are some models where a Q8 quant dramatically changes what you can achieve compared to fp16. (I'm thinking of the Wan video models.) The point I'm trying to make is that it's a noticeable model change, and can be make-or-break.