I always struggled with the fact that I was told these things were wrong, but I could never see in practice the reason for their being wrong. Murder, stealing, yes, I can see those practices having bad results, but congratulating someone for making it another year in their limited time on the earth? I could never see anything negative about it.
When I was a child (of the 70s) I would hear this: "birthday parties bring too much honor to an individual". That made sense when I was 8 years old, but as my brain developed, I was like: "anniversaries honor two people", what the hell is the difference? Parental answer: "marriage is an arrangement of God" that's why we have anniversaries. And it was just stupid apologetics like this that aren't even in print that I would hear.
Most JWs know that there is actually nothing wrong with birthdays, thus the cognitive dissonance.