The past is finished. There is nothing to be gained by going over it. Whatever it gave us in the experiences it brought us was something we had to know. ― Rebecca Beard
Those who cannot remember the past are condemned to repeat it -George Santayana
Less nonsensical, but still.
Things are not black and white or green and blue. Forgetting the past and not knowing history opens one up to manipulation by others (and lots of current examples of that - starting with "bringing Christmas back to us"). But dwelling in the past is to deny the life we live now.
Happy New Year to One and All