Some of those elections were sort of close, definitely not a 2000, buit also most definitely not a 1964, like 1860, 1868, 1900, 1988.
Why do you think 1988 could have been winnable for Dukakis? In the minds of many voters, that may as well have been a third term for Reagan.
Without some of his gaffes, it could have been a closer race. Actually, Dukakis only lost by about two to three points in three major states (CA, PA, IL). If he had won those three, he would have had 207 EVs instead of the 111 EVs he actually won. So like I said without some of his gaffes, it would have been a closer race.