Page 72 of the PHB. Are you denying that RAW has those as the fighting styles?
I said no such thing, I'm saying that each of those styles represents far more than a single style.
Great weapon fighting covers 11 weapons and the Naginata is not one of them. I suppose the DM could bring that in as a home brew weapon, in which case it would fall under the one style of Great Weapon Fighting.
Check the monk section, under martial arts. Note how they say that other weapons (such as the kama) would use stats of weapons that are on the chart, in the case of the kama, the sickle.
So, no homebrew needed.
I know how long they take in the real world. However, 1) D&D is not the real world. While you can apply logic and common sense to the game, you cannot expect it to mirror reality. 2) Monks, not Fighters learn martial arts. And yes, I know that technically weapon fighting is a martial art, but that's not how
@Chaosmancer was using the term when he posted his ridiculous list, and 3) the game says basic ability, not mastery.
1) Logic and common sense are being applied, different styles apply to different weapons, over time and over geography, because people develop different techniques. To deal with different weapons, different armors, different opponents. The style of swordsmanship in Waterdeep where the nobles duel as gentleman is different than the style of the Silver Marches where they fight lizardmen in the swamps.
2) I know how I am using the term. Martial Arts is not limited to hand to hand combat. Every weapon style is a martial art. Martial meaning "appropriate for war".
2a) If you had looked at the list in detail, you would notice that every single one was regarding weapon use, not hand to hand combat while unarmed.
3) I never claimed mastery. Basic ability in a few hundred or thousand styles is more impressive than mastering a single style.
But, it is clear from your responses you don't care about what we say. You have decided you are correct after all
Multi-classing limitations? No multi-classing allowed by that DM? Not enough experience? Other reasons.
Lack of desire? Lack of any of the above? Other reasons.
Knowing how to wear armor and wield weapons in a world where monster attacks are common threats to your life is something that people won't pursue do to a lack of desire. But magic that can make their lives easier is something that everyone desires.