Let's see if you can understand a simple concept:

The President of the United States is the only government officer elected by all the people of the United States.

Donald Trump and Joe Biden are running for that office.

The Supreme Court is one of the three co-equal branches of government. The actions of those who serve on that bench have a direct effect on the lives and future of all of the people of the United States, therefore it is the right of all the people of the United States to know BEFORE they go to the polls what each of the candidates intends to do on behalf of the people of the United States.

And, that includes who each candidate intends to appoint to serve on the SCOTUS bench.

History Is on the Side of Republicans Filling a Supreme Court Vacancy in 2020

Excerpt:

Twenty-nine times in American history there has been an open Supreme Court vacancy in a p**********l e******n year, or in a lame-duck session before the next p**********l inauguration. (This counts vacancies created by new seats on the Court, but not vacancies for which there was a nomination already pending when the year began, such as happened in 1835–36 and 1987–88.) The president made a nomination in all twenty-nine cases. George Washington did it three times. John Adams did it. Thomas Jefferson did it. Abraham Lincoln did it. Ulysses S. Grant did it. Franklin D. Roosevelt did it. Dwight Eisenhower did it. Barack Obama, of course, did it. Twenty-two of the 44 men to hold the office faced this situation, and all twenty-two made the decision to send up a nomination, whether or not they had the v**es in the Senate.