Then Target, Walmart and the corner supermarket should all cease to exist because in the end, they’re just asset price speculators.
They buy an apple for 5 cents and try selling it for 50 cents. They don’t even do their own shipping any more, the vendors and middle men have all that responsibility.
If you think they generate value by making availability, then you’ve just provided your answer.
As for a ‘few’ market makers, wow, learn history. The fewer the market makers more illiquid and the higher the spreads and their profit margins.
You can get that education any day from either trading a thinly held stock or dealing with a real estate enclave that doens’t participate in the MLS or buying a car or any other product with only a few distributors.