When you run to the right, and the people who like right-wing policies already have a party giving them the policies they want, they're not gonna switch parties, and you're just going to alienate the parts of your base/coalition that are affected by those policies.

Campaigning primarily on being the lesser evil and maintaining status quo failed, you can tell people 1 choice is slightly better all you want but on election day we found out that you can't win that way. If the dem politicians actually want to win they'll try a different strategy next time