Beta's been said to be composed by people that react with Fe+ to Se- (static extraverted negativist and introverted positivist that are the engagers), so without the presence of Se- their Fe+ will generally appear to be forced. That is also why groups composed only by Beta NFs are though about as being excessively "dramatic". The presence of the statics don't calm down the dynamics but provide and input for the "drama" to be executed without looking stupid. Notice how for example ENFjs are said to need to burst out their emotions even via laughter in order not to explode. In absence of something capable of creating an atmosphere of "bursting" they might just look manipulative.

Anyway, just random thoughts without a real order.