The reason for it has to do with the fact sound and sight are different in BG3 then it is in tabletop. When you cast a spell of invisibility, you are not invisible because the enemy can not see you, you are invisible because you are unable to be detected by senses outside of magical ones- tabletop. Now Larian fear this like the plague, so they interpreted them different. Invisibility is protection from sight, not from being heard. Sneaking is protection from neither, as you break los.
Do I think such changes make sense? NO. There is no reason why every enemy would be able to attempt detect you multiple times without a penalized check- if i already cant see anyone, I am in a state of ignorance, rolling a check for hearing should be a -2, and then another check at -4, then -6, and then -8. Instead enemies make each and every check at normal, so you can hide, but get instant caught by their 2nd, third or forth check
