Hydration is important so I'm with you on the first half, but what is the proposed link between reduced creatine intake and emotional wellbeing?
If you can say "Oh yea that makes sense" with the same set of knowledge you had both before and after some event happens, all else being equal, you have an expectation. That is enough for placebo.
You have to have literally 0 knowledge about an event to rule out placebo.