A lot of the people I knew doing "full-stack" (which just wasn't a phrase back then) 5-10 years ago basically were still much stronger on one side than the other. I knew a whole bunch of guys who could build you a beautiful - for the time! - Flash site and they could store data via PHP into a MySQL database and they could deploy it on a server (and then they could send you an invoice! Seriously, totally full-stack)... but my goodness would you not want to look too hard at the PHP, because little Bobby Tables would have cried.