It's simply an abbreviated version of Elongated Muskrat as far as I'm concerned. Payroll is easily one of (if not the) most complex systems at any company. It's not just statutory stuff but personnel stuff as well. With Twitter you're not just dealing with 50 states and the feds, but with every other company in which Twitter has (had?) employees. There's a cottage industry of payroll firms precisely because payroll is so obscenely complex.
Even if you outsource it you'll still need people within your company to manage your service provider. At one company I worked for they got all of their outsourced HR+payroll for free (indefinitely) because the provider (Gevity) consistently fucked up everything they touched. This was at a company of like thirty people.
If you're suggesting Twitter can simply outsource payroll, sure. But you do that before you fire your whole payroll department. You still need people to handle the transition.
Even if you outsource it you'll still need people within your company to manage your service provider. At one company I worked for they got all of their outsourced HR+payroll for free (indefinitely) because the provider (Gevity) consistently fucked up everything they touched. This was at a company of like thirty people.
If you're suggesting Twitter can simply outsource payroll, sure. But you do that before you fire your whole payroll department. You still need people to handle the transition.