In all my professional life, I've never once found work through an employment agency, which I think are disgusting parasitic, often offshore outsourced, rancid vermin. Every job I've had has come from word of mouth or direct ad by the employer. Intermediary agents are horribly stupid. I've never blown off an interview with a company that does show interest, but would happily do it with a recruiter given I have zero respect for them.
On the other hand I understand being ignored by employers who don't reply to job seekers. I think I've had only three negative replies to job inquiries in my life, the rest just leave you hanging. So I can understand the "bale if not better" mind set. If employers want to be taken seriously then they need to at least play nice with potential employees.
However in today's thrifty world, sending out N negative replies by post or even email is often too much a burden (hassle) for a business, so they leave applicants hanging; only fair turn around if an applicant does like wise.