Monkeytron, the mods he's talking about are made by people in the community and the mods are aware of them and what they do so as long as its a purely visual mod like dark mode then your runs will get accepted
I'm not one of the mods but to me it feels like recording with phone can lead to bad quality, you could say you can then only accept the runs with good quality but then it becomes subjective which isn't a good thing
I also can't really see what way of cheating wouldn't be obvious when using OBS but would be obvious when recording with phone
Overall I can completely understand frustration with this not being allowed and I would maybe like to see it change as well but those are just some points I came up with at the moment for why it shouldn't be allowed