For myself and most others that actively use LLMs, I’m aware of the model names and differences, and on the off chance I don’t, I can do a quick search to find out.
On the other hand, my dad (“average user”) probably doesn’t care whether to use Argon or Pro, or Flash for that matter. They are all good enough for his use case anyway.
I suppose the “Auto” option is what AI companies expect the average user to use.
I think in many cases people may not be very AI pilled / be looking at artificial analysis etc and might think "I'm doing this much harder task, let me use the best model" and they may infer from naming that 3.1 Pro is better than the recent flash models which would be incorrect.
Anthropic had an issue with delaying the release of a new Haiku for ages but it didn't really mess with things as it was always the weakest model and so positionally it stayed the same. If however they stopped releasing new Opus models and somehow Haiku started overtaking Opus I think it'd confuse the normie consumer.