Why is the protection fighting style considered subpar in D&D 5E?
Protection fighting style is a bit redundant in 5E while following certain classes because it doesn’t necessarily enhance what the class does well.
Even if you’re using a martial monk, or a trickster rogue – who can plausibly use the protection fighting style’s features with their respective abilities – it just feels like an overkill if your goal is to be able to fight. Especially since these two instances of these classes are melee-focused which isn’t considered to be one of the best styles by most gamers and players. In other words, there are far more effective styles for both groups that have features which are better suited for their respective needs within combat situations.