Also from what I've noted is that when you sign into a secondary account on the main profile's account, Chrome is prompting you if you don't want it to create a new profile for you.

Then again, they have the problem that they think that it's appropriate to open the last used profile if you start Chrome again, which can lock out inexperienced users out of the other profile since they don't know how to get that one started.

For me the normal solution of creating separate profiles in Firefox is to use Firefox Portable and have each profile live in their own directory / installation.