Why do some keybindings not have the delete (-) button to remove?

I'm trying to edit my keybindings in Xcode's preferences. Sometimes when I click a binding, I get the "-" button to remove it, but other times I don't.

For example, in Xcode 12 now, the shortcut for "Analyze (Product Menu)" has no way to remove it. I rarely use this and I don't want it taking up a binding.

(I also wish Xcode would allow multi-stroke bindings like Emacs and IntelliJ. I can make more mnemonic bindings that way. But that's another story.)
Why do some keybindings not have the delete (-) button to remove?
 
 
Q