It might very well mean magical solutions suffer more and more severe restrictions than non-magical ones. Magic is the wildcard, the game design can do what it wants with it.
However you decide that should work, it needn't get in the way of the game being fair (better yet, balanced).
Sentinel is not a good feat. For instance, because it burns your Reaction, which you also need for Protection Style. Heck, the 5e handling of Reactions is pretty bad, generally, making play too turn-based, too much like you 'freeze' when it's not your turn.