im with you, mostly
jabs are useful, but lets be clear they are useful mostly to back the other guy off or to distract him whilst you do something else
it is possible if your jab is hard enough and fast enough to jab someone to defeat, possibly be TKO but certainly by points
but to do anything much it has to land ( obviously) which requires speed and needs to hurt them enough to distract them or back them off.
a powder punch jab isnt the best, it is arguably better than not landing at all, but not much. but its not an either or situation and fast jab will impart force, a faster jab will impart even more.
if what your doing is throwing a straight ? right/left rather than a jab, then that really depends on if your straight right is fast enough to land, if it is, great, if it isnt stop throwing straight rights and work on your jab