I suppose another strongman would be that LLMs substantially decrease the cost of human creation (i.e. the HITL assistant use case) while producing an output of equivalent quality.
As a result of this, everything gets cheaper and more plentiful.
The counterargument I'd make to that would be the requirement that the human have creative skills, which might atrophy in the absence of business models supporting a career creating.
Generally, having cheap mass produced things can be great compared to only expensive artisanal stuff that only the rich can afford. Think about furniture, clothes etc. or all the other stuff you have in the house, compared to 100-150 years ago. Today we can buy pretty good mass produced furniture for example. A few generations ago people either did it themselves in a wonky way or paid a lot of money for a hand made carpentry option. Just like with LLMs. LLMs probably do a better job in general writing than a random person off the street. But it's not as good as the top performers. But it's much cheaper. It's a tradeoff.
The difficulty is the biggest gains there are for singular goods which can't be copied at low cost.
Exquisitely designed piece of furniture = expensive copy
Well-written book = cheap copy, post-printing press
So we're not necessarily going to get "more access to better" (because we already had that), but just "cheaper".
Whether that hollows out entire markets or only cannibalizes the bottom of the market (low quality/cheap) remains to be seen.
I wouldn't want to be writing pulp/romance novels these days...
So I'm not exactly naive, but we should then discuss this instead of the red herring of copyright.