light and shade (Unryu-in temple, Kyoto) by Marser
Via Flickr:
1/250s f/5.0 ISO400

Φοβάμαι να πηγαίνω πια στα μέρη μας. Σε αυτά τα δρομάκια που γελάσαμε, ανταλλάξαμε βλέμματα, αλλά ποτέ δεν μιλήσαμε για αυτά. Μου αρέσει να σε θυμάμαι, αλλά πονάει.
GT Sans Theory

I have mixed feeling on the theory, as I feel bad for Mattpat because he was gonna get screwed either way. If he did what all the evidence in the game suggests and made it about Sans being someone in a skeleton costume, he would get hate for doing what tons of people already theorized and what many fans already know, and some people are very against Sans being not a skeleton, because somehow a skeleton is more erotic than any monster/human/whatever inside the suit, and it would ruin a lot of fanfiction, or whatever reason leads to people being in denial and assuming Toby was just really lazy and didn’t make many edits to Sans face sprites and other stuff like that. I don’t know why it really matters, Sans could be anything inside that costume, and it’s not like it would change his personality or powers.

So Mattpat had the other option of making something no one would claim they came up with, something new. The start of the theory is pretty good, the badge and the friends and 3 figures seems pretty cool and it would make sense for Toby to put in more ties to Earthbound, but the whole no organic issue with the machine completely ruins the theory, as it would just transport a human soul and a pile of bones, not a living skeleton with eyes and such, plus Papyrus is a monster, as shown by turning to dust, and star men do not have human anatomy or human skeletons, if I remember correctly don’t starmen have one eye? The battle body with the starmen symbol is a definite reference, but it just doesn’t make sense. Ness doesn’t act like Sans, Sans acts older, and the whole thing doesn’t explain Gaster. I could go into every major hole in the theory but it’s already been done.

To be honest, it’s a futile thing to try with so much missing and Toby still adding details. Mattpat couldn’t leave it vague without facing disappointed fans. There is not a good choice in this situation. Personally I would go with the done to death theory, even if I didn’t make it all by myself or be the first to make a post about it, and I would leave it vague, and those choices would probably disappoint people, just as it would disappoint even more people if I said I was putting it off till Toby adds more about it in the game, something that might not ever happen. It takes a lot of time to play the game, go through everything, come up with a theory, test everything, design the art and video effects, make a script, record it, make the actual video part, and upload it. It’s so much easier to type up stuff and post photos, and much faster.
Mattpat is probably so over the fandom games like FNAF that he might not make another Undertale theory. Fans get pretty toxic and annoying over this stuff.