https://en.wikipedia.org/wiki/Delegation_pattern
In delegation, an object handles a request by delegating to a second object (the delegate). The delegate is a helper object, but with the original context. With language-level support for delegation, this is done implicitly by having self in the delegate refer to the original (sending) object, not the delegate (receiving object).
Di wiki yang atas ini bisa dilihat bahwa delegate itu harusnya dikirim dengan original context, yaitu sender context.
Kalo di MVVM, sender itu si View Model-nya. Juga disebutkan caranya adalah dengan mengirim sender(VM)-nya itu sendiri.
https://en.wikipedia.org/wiki/Delegation_(object-oriented_programming)
delegation refers to evaluating a member (property or method) of one object (the receiver) in the context of another, original object (the sender).
Article yang ini memperkuat aja bahwa yang dimaksud delegation itu bermain (evaluating) dengan member of the receiver (VC), tapi dalam context the sender (VM).
https://developer.apple.com/library/archive/documentation/General/Conceptual/DevPedia-CocoaCore/Delegation.html (Somewhat deprecated though)
The delegating object keeps a reference to the other object—the delegate—and at the appropriate time sends a message to it. The message informs the delegate of an event that the delegating object is about to handle or has just handled.
Kalo article ini punya Apple somewhat deprecated, tapi masih relevant harusnya. Dalam context MVVM, delegating object itu VM dan the delegate itu VC.
Jadi dalam context kita article di atas bisa diartikan begini, VM mengirim message ke VC untuk meng-inform akan sebuah event yang akan/sudah di-handle si VM.