Indeed, BUT how often do you get pushed into a situation where you have no options even with flight plan fuel.
We tend to look at flights as being A to B divert to C.
The reality is that we often fly past perfectly suitable airports enroute where if turns to crap we can bail out to. Obviously the bigger the aeroplane the fewer the suitable airports but nevertheless the reality for most domestic flights in Oz is that we only really get fuel critical in the last part of the flight after we fly past the last usable enroute airport.
Assuming we are paying attention to the weather at the various airports then the weather has to turn to crap suddenly after the etp between that last suitable airport and the destination for us to be really in trouble.
So the big strict liability bogey man isnt a big a threat as many think, in my opinion anyway.