Scaling rewards the player's engagement and skills, while no-scaling rewards time and effort put into levelling your character. Both have their ups and downs, and most games use a hybrid implementation with some leeway for the scaling (skyrim for example).

In my opinion Skyrim is one example of it being done badly. Partly because not seeing weaker enemies anymore breaks immersion, but mostly because any attempt to engage with the non-combat systems will break your power curve. If you take Smithing from 10 to 80 for example, that's 8 levels the enemies now have on you. So you have to be using Smithing a lot to make up for that. It's worse if it's something like 150 points over Lockpicking / Speech and Pickpocket which have no benefit in combat. That's another 15 levels the enemies get, and it's even worse if you switch from one handed weapons to two handed, or change armor types at any point.