Looking at the schematic didn’t make that clear, there must be more to it.
I have touched transfer bar pistols.
And maybe taken a few of them apart.
The hammer can only fall so far before it stops; it hits against the frame. The hammer has no firing pin on it (like original Colts did).
The transfer bar, if present, fills in the gap between the flat-faced hammer and the firing pin (which is located in the frame).
So, if the transfer bar is gone, the hammer stops, no transfer bar to fill in the gap to the firing pin, and there would be only a loud ‘snap’.
Not a crying, whining voice ‘i did not touch the trigger’.
The trigger, when pulled, raises the transfer bar to fill the gap, on pistols so equipped.
Does this help?