It must be true. This since when a thought enters our mind like "let's get wasted" we can't think of all the reasons why to do that thing.
But if we can't think of a reason why not to do it then we should do it as doing things is obviously better than not doing them. Also it makes for more efficient speech.
Obviously if you think of something better to do than get wasted (or a reason not to do it) then doing that other thing is better and you ask yourself "why not do this other thing" upon which you either do that thing, don't do it due to a reason or do a better thing, etcetra.
Fuck yeah
Example:
Person A: Why not get wasted!?
B: Cause it's way more awesome to play ping pong.
A: Agreed. So why not play ping pong?
B: No reason, thusly we shall play ping pong.
This is superior to:
A: Let's get wasted!
B: Why should we get wasted?
A: Cause it's awesome.
B: But it's more awesome to play ping pong.
A: Agreed so let's play ping pong.
B: OK.
