I think it's a matter of pride and insecurity generally. The first player to do any new skill is taking the piss or offending, until it becomes more accepted. Nutmegging a player is no longer that much of a code thing, but that's quite a primal one that feels embarrassing or offensive.
Neymar isn't doing things outside of the rules or even against the nature of football. He is the beautiful game in action and he frustrates, he taunts, he showboats, but he's the most flamboyant player. He puts the fear into people by threatening to embarrass them, so they don't want to engage or do so cautiously.
If you watch some of the clips from his time in Brazil, he is well used to get absolutely twatted all over the place.