I don't claim to be as good as someone with six years of experience (I'm not delusional). Nor am I claiming that there are no companies that need to hire senior engineers. I'm well aware of many types of problems for which I am not qualified to solve. What I am asking is, does EVERY company need to exclusively hire senior engineers? I've interviewed at companies whose product was not much more than a CRUD app, and, despite performing fairly well in a technical assessment, was rejected for lack of experience (even though they could see how much experience I had right on my resume).

Most companies don't need the best of the best of the best. They can save a lot of time and money by hiring someone who, with just a little bit of investigation, they know is going to come in with some decent technical skills, and can quickly learn to become a valuable asset.