For engine gurus: Why overfilling oil is bad for engine?

[Delboy]

Originally Posted by M-A8

...sooooo, I've noticed no difference after leaving dipstick out for 35min, still about 2mm above the MAX line.
Would you classify this as a possibly dangerous overfill???
I can't see 2mm being dangerous personally purely because a 2mm mistake is so easy to do and having gaskets blown each time you overfill by 2mm would be mad

Wah wah wah, Warning failure imminent, failure imminent Wah wah wah

Only kidding I'm sure 2mm will make no difference Marcin