The statistic of 80% of companies not responding is pretty stark. I'm curious if you applied exclusively to start ups. I think the "resume black hole" complaint is a pretty common one, no matter the size of the potential employer. If you're applying online, to relatively larger companies, there might be more feedback available to you than you might think.
Here's my 2 cents:
I'm part of a start-up (StartWire) created by former HR professionals, aimed at dealing with the pain point of not hearing back from employers. We work with the resume submission platforms used by most major companies to provide feedback to applicants - from confirmation that your resume was received, to notice that you've been disqualified or that the job is no longer posted. This isn't going to make you like a potential employer who couldn't find the time to get in touch with you personally any better, but it could give you some valuable feedback as what is going on when you don't hear anything. Maybe something about your resume has gotten you frequently disqualified before a person ever sees it. Hopefully it can be a helpful idea to those who are frustrated by the current process.