'certain' in this context means: those H1B holders who have completed 6 years of the original visa term. They are compelled to either wait and languish in line, or go back home where their spouse can work.

Edit: Not sure why I got downvoted. I was just paraphrasing the reasons given in the proposal. Its not an opinion. Don't shoot the messenger. See http://www.reginfo.gov/public/do/eAgendaViewRule?pubId=20131...