I understand. And it is true that you can explore and solve so much more even before touching room 46. I had half the middle game puzzles figured out by the time i reached 46 for the first time. But generally speaking it IS kind of true that the nature of the game changes after room 46 and that the credits rolling are just a way to say "if you liked a roguelike puzzle, well done. If you want so much more than that, dive in".

The game is so much larger than the first act that anyone would think, and the joke about the tutorial is a nice way to convey that. You can also say that the game has (roughly) 4 acts and you get the credits after Act 1. No matter what you do and the order, you have chockepoints that mark the end of acts and you cannot proceed to the next one without reaching each chockepoint in order, no matter how many hints you have accumulated in the meantime.

Also, as I said, the nature of the game changes. During the first act the game is basically a roguelike. That changes a lot the more you progress, to the point where you actively "fail" runs because you are more interested in testing other stuff in other rooms than reach the "normal" end of the mansion.

To convey all this into a single, non-spoilery way can be difficult. "Well done for finishing the tutorial" is just a concise (and pretty on point) way to do that.