The "without affiliation" aspect is a dealbreaker in many fields. Lots of journals won't even acknowledge you if you're not at an academic institution.
It's not a dealbreaker in computer science, where the norm is for blind peer review. And in any case, you can just list your undergrad institution or a company.
Actually, I think you'll find there are sufficient number of mid or lower tier journals that will send these out to referees. I've refereed papers from non affiliated researchers before. And even Nature will send you an rejection letter.