Come on now, just because I point out those who disagree are wrong doesn't make it 'fireworks'!
1) when you decap BEFORE you tumble in a vibratory cleaner, you don't get the benefit of clean primer pockets -
I can live with the fact my pockets aren't spotless but when I decap/tumble doesn't change anything.
2) you end up with corn media sticking in your primer pockets and flash holes. Not in every piece of brass, but in some -- and a piece of media stuck in either of these places can & often does displace or snap a decapping pin later when you attempt to resize.
I find running a sizer with decap pin does a fine job of punching out the occasional kernel of cob and have never broken a pin doing so.
3) decapping before tumbling in a universal decapper adds a whole 'nother step to the process, and that's a LOT of work as the number of cases increase. That's one more hand motion in to a shell holder, ram up & down, and case out of a shell holder. For no benefit?
I guess "benefit" is in the eye of the beholder. Time lost messing with my Ultrasonic and drying cases eats up MUCH more time than the simple extra decap step.
4) disagreeing with anything wncchester posts is always good for some thread fireworks. Even if you try to let him know it's just friendly ribbing!
You gotta realise a lot of my responses are with grinning, never snarling!