Because you have the command-line + browser at the same time. You can quickly copy, view, move files. Change quickly to folders remembered in history. Go in archives, copy, view from there to outside. Sort by various things. Execute directly files.

For example, if I need to run one exe, not in my PATH over some file, I have them both in left and right window. I go to the left, type "Ctrl+F" - e.g. get me the full name (in this case executable), then go to the other window, type "Ctrl+F" again - get me the file to become first argument on the executable and run.

Ctrl+O (in midnight commander too), switches to almost fullscreen command-line - so in a way it's always better than just a command-line.

Search in Files, compare dirs, and many other features (there are tons of plugins).

Also checking SMB shares, FTP, System Processes (though I prefer SysInternals ProcExp.exe there)

I use the Windows Explorer (the file manager) only for very few things - certain context menu items, some forms of preview. It's always there by typing "explorer ." from the current folder.

Having tabs is a big reason for a lot of people that use a different file manager in Windows, at least for the people I talked to about this.

The same reasons one might use an alternative file manager on any other OS: because their workflow suits it better.

One reason might be performance on low powered devices.