Did anyone really think Apple was going to release a 16" model without an event? Why on earth would anyone think that?
The real question is: did anybody really think that Apple was going to release a 16" model
on its own this year that only differed from the 15" by a slightly bigger screen (the existing screen is 15.4" so not necessarily even a full inch) and a new keyboard? The answer is
yes because of multiple rumours supposedly from reliable industry sources apparently confirmed by icons of a 16" MBP turning up in Mac OS 10.15.1 beta - something you wouldn't expect secretive Apple to include until the last minute before launch.
Once you accept that as a possibility, then all bets are off, because it would be a somewhat irregular thing for Apple to do
anyway. One quite plausible conclusion was that they'd rushed forward a future design in order to address (real or perceived) problems with the keyboard - plenty of people have pointed out that a keynote consisting of "Er... the screen is bigger - look, I'm holding a tape measure to it and, um, well the keyboard doesn't have the problems that the old one, er, didn't have..." might best be avoided.
Or, of course the 16" might still be launched tomorrow, or next week, or March, or WWDC, or WWDC
2021, or Apple might turn up at the Thanksgiving parade with a Mac-shaped float. No laws of physics would be broken. A 16" icon still appeared in MacOS without any hint of (say) a matching 14" so the game is still afoot.
Thing is, we all have lots of fun trying to read the tea leaves and predict what Apple is going to do based on inconclusive hints and rumours. Then some people spoil it by declaring that their personal reading of the runes is the absolute truth and everybody else is wrong and foolish...
Nobody who actually knows is likely to jeopardise their career, and nobody who anonymously leaks commercially sensitive information can be 100% trusted.