There is an existing question about why the democratic convention is so late, with both answers focusing on it not actually being much later than usual and how generally the situation is resolved quietly and quickly.

So focusing on the general case, given that the state deadlines are a matter of public record via the state legislation why does this continue to happen?

It seems fundamentally unserious to conduct a general election requiring quiet fixes every four years to enable the candidates to be voted on.

Why have the parties and states not moved to resolve this by ensuring all nominating conventions happen before state deadlines by either shifting the conventions or the deadlines?

Biden on Ohio ballot?