I wouldn't think a giant job and resume board needed this many people to run.
OTOH, as was pointed out earlier, it looks like a chaotic, noisy environment. If you have that kind of environment, you may need to multiply your team size by 1.5, at least.
edit: from http://careers.theladders.com/ it looks like they are using Java, Spring and are fully enterprisey buzzword compliant (only missing an Oracle RDBMS). If that's the case, you can multiply your team size again by a factor of 3.
edit 2: talking with a colleague from another company (they do a lot of Ruby stuff) I could confirm that our two-week sprints (we do mostly Java in this cell) are too long for them. Your iteration time varies according to the tools you use.
Looks like it would be very noisy too, headphones a must.
This is how you typically run a 'sales & marketing' office in NYC, by being open. Just surprised to see devs that are in that mix.