I quit university after my 2nd semester co-op during undergrad (to work at my current firm), I have since been promoted four times and now work as a senior engineer (though I cannot technically use this title). Trying to move firms now after working for 5 years, It is incredibly difficult for other firms to accept that I've been working in the field successfully given that I do not have a completed degree. On one hand, I have skill now that I could have never earned in school - on another hand I may have gimped my ability to move deep into the upper half of the first six figures salary.
I think it's because of the salary level - like HR/management cannot get their heads around paying someone who doesn't have a degree the kind of salary that developers get these days.