If a team has swung the disc across the field twice (across and back), it hasn't gained ground. Unless there is good reason to do so (e.g. it puts a strong thrower in position for a big gainer), you have risked turnovers without heading to the place you want to be: the endzone. Ideally your offence is structured so this happens a small number of times.
And I feel this is best addressed at the origin: beginners.
For the beginner, they need to build the confidence to throw forward. Being regularly urged into a 3 metre back pass by a nagging veteran is not useful. Each mistake throwing forward helps them throw better. If they can't complete simple forward passes more than 50% of the time, they need lots of throwing practice. But that is a steep learning curve they will quickly rise up.
Training beginners to only look for a backwards pass makes them predictable, limits their throwing range, puts blinkers on how they see the field (and don't we all want better field vision?), and discourages them from looking to break the force.
There are few games where a beginner is playing, and it is critical they throw their safest pass every time. If they are in a game, it is probably a good place to develop their throwing skills.
The backwards dump has its place as a reset of the offence, but only as an occassional tactic.