It seems it's mostly obsolete now anyway? I've seen people reporting that after patch 1 most mods work without it (after getting frustrated by nexus drama and removing it entirely), there's just the data error message, which you can ignore.
It's still as necessary as it always was. There are two possibilities for people claiming they don't need it. The first is that the mods they're loading genuinely don't need it; it's always been the case that some mods aren't loaded as mods but are just loose files (even when included in a pak) which then overwrite game files on launch. These mods could always be loaded without installing them (that's how the Mod Fixer itself works). Some mod authors erroneously claim they they need(ed) the Mod Fixer when they never did.
The second possibility is that they have a mod installed that has the Mod Fixer prepackaged with it. Some mod authors do that rather than requiring the Mod Fixer as a separate download and don't always say that's what they're doing. This means the Mod Fixer is actually installed and people just don't realize it.
