I think their main point is that trying to get users to use _your_ chatbot is a losing battle since 1) people are more familiar with/have lower friction interacting with mainstream/first party chatbots and 2) this is similar to when sites tried to establish a first party relationship with users via bookmarks but lost and became second party to search engines.

They don’t provide metrics but the analogy seems reasonable to me.

What metrics would you be looking for?

Would they be hard to find/gather?