Don't feel bad. This is a really important distinction that many tutorials don't cover: the line between "Collision Checking" and "Collision Handling" is often blurred. TDMC is a collision "handling" system. It utilizes place_meeting as it's "collision checking" function, but all the logic AROUND the calls to place_meeting are what you are really paying for when you purchase TDMC. Collision checking is pretty simple: "Is there something there or not?", while collision handling is really complicated: "Okay, there is something there... what do I do about it?"
Once you understand that these are two separate pieces to the puzzle, it makes more sense that you can simply replace "place_meeting" in any tutorial with a custom script, and get similar behavior with more control over what is a "blocker" and what isn't.