When someone tells you it's evil to do something you know is harmless, then it does tell you they haven't a clue.
But, if one values enjoyment, good times, life, friends, then because of that valuing and because that human nature has some universal (to humans) constant qualities, it follows logically then there will be principles (merely because human nature is consistent).
See the post just above for the perfect forms of what is best in practical actual living -- the principles that cause the best outcomes. (the highest overall degree of enjoyment, peace, friends, thriving)
It's sort of like how plants need water, soil, sunlight. Give them what they need, and they will thrive.
Like that.
Re Matthew 7:12, i modify that based on experience... Do unto others as you would have them do unto you... Only do it first?