1) the suggestion that Biden should resign from the presidency because he is standing down from running. Biden is not saying that he is incapable of running. He and his team just understand how to read polls and don't want their party to lose the election which seemed almost certain with him at the top of the ticket.
2) the suggestion that Biden stepping down is subverting the will of the primary voters. There was no real 2024 democratic primary just like there was no republican primary in 2020. There were no serious candidates and no debates. I am sure there are Biden supporters who are disappointed and angry that he has dropped out but it was his choice to make. If he had stayed in the race, I am sure he would have secured the nomination. This wasn't taken away from him. He voluntarily stood down. A candidate should not be obliged to remain in a race just because they won a primary.