Why do people think the show being in a psychiatric facility wouldn't be the lamest twist ever?

People think Tabitha is in an asylum and dealing from the trauma of losing Thomas, personally i hate this theory, i think if it came true it would destroy any stakes the story had, all the deaths would've meant nothing and all our favourite characters and stories never would've existed, that's not a twist, that's a cop out. That's a Rick Grimes is still in a coma theory, that's a "character wakes up and it was all a dream". What's happening needs to be tangibly happening to real people or is was all for nothing.