LOAD_CLOSURE is identical to LOAD_FAST_CHECK in every way except its name and number.

The justification for its existence is that "We keep LOAD_CLOSURE so that the bytecode stays more readable.".
Which is insufficient justification to keep it given that it:

• Uses an instruction, a limited resource which adds bulk to the interpreter
• Prevents superinstruction formation.
• Prevents removal of checks for uninitialized variables.

Linked PRs

• gh-105775: Convert LOAD_CLOSURE to a pseudo-op #106059