I think it's not so much the individual launches that annoy people as the fact that there are so many at once. It throws off the usual mix on the frontpage.
Launches are interesting to a general audience.
Jobs only to a small niche.
This is what annoys me the most, especially if it's a 'stealth' idea or it's a YC company that posts once a month instead of using the "Who's Hiring?" thread.
But seriously, tech startup launches? As opposed to another shallow-but-emotionally-intense political discussion? Easy choice.
Doooooes their name begin with a number?
Do they wear glasses?