Those are "niche" maps.
Generally we have 4 main maps in AoE2.
Arabia - main land map - niche alternates are the ones you mentioned
Arena - main walled map - niche alternates are hideout and hill fort
Team Islands - main water map
Hybrid maps such as cross or continental / medi
All the bottom civs in Arabia are good at one of the other main types of maps. All except Magyars.
Turks, Portuguese good on Arena
Italians, Portuguese good on Team Islands
Magyars are clearly meant to be a land map civ but they're just not good at what they were designed to do. In other words, they're a poorly designed civ. They're not good in Arena or water maps or hybrid maps. But they're also among the bottom ON THE MAP THEY'RE SUPPOSED TO BE GOOD ON.
Do you now understand the flaw in the logic regarding this civ? With Italians you can say, yeah they suck on Arabia BUT at least they're good on water maps. There's no but for Magyars. They're just bad.
I think you are conflating Magyars being bad with walling being too easy. Magyars are good at what they were designed to do, but what they were designed to do is not very good with how the game is currently.