Loves "Friendly Girls"
The answer is a combination of "Don't worry about the realism, that's not going to result in a fun story" and the actual sorta truth: She started playing on launch, and the game design was based around a bunch of skills and equipment that only one person can ever get and she just happens to keep finding more of them that stack in hilarious ways.The show in general is entertaining and cute but her continually moeing her way to more and more means of Invicibility says both about the character writing and fake games design they live in. In short: how is she the first person to make this broken build and by accident to boot. Either this game was destined to fail in a matter of months or I just need to dial my suspension of disbelief to broken Tier levels and try to enjoy season 2.
Also like, the conditions for some of the things are so dumb that it makes sense that they're pretty strong. The anime glosses over the passage of time, but frequently Maple is doing the same sort of thing for literally hours. The first skill she gets has the condition of "Be attacked for an hour and don't take or deal any damage". No one's gonna do that. The game devs are dumb. Literally any scene they show up in is essentially "Look at that, it's the consequences of our own actions."
VRMMO stories pretty much don't work if the devs actually worked like game devs. It's the kind of thing you have to let go, like whatever kind of magic nonsense is going on in any other show.