If you don't already have 25 stacks of vulnerability on the boss, getting there will do more damage than anything a shortbow can do. That's my premise. A quarter more damage to EVERYTHING is not a mediocre bonus. Also the vulnerability plus bleeding is far a better use of initiative if there is not already max bleeding. Let's agree that it's a situational weapon set. Shortbow is usually not ideal for boss fights.
I'm talking pure damage, but if you want, p/p can offer you blind and interrupts, and SB can't.
Different situations. But shawn will drop some gw1 credentials and cite a 4chan meme and we're all wrong.