[babul]

Your reputation is only as good as the people who know it. Most HR will not have heard of you (unless you are a high-profile leader in your field) and hence the desire for a rubber stamp from a brand company. It's the same reason many people desire Ivy League education, not for the learning, but the brand name that will make entry to most jobs a lot easier (as HR/Company assume certain level of quality/competency/work-ethic/etc has been met).

[tomjen3]

HR doesn't need to know you - they just need to be told "I want to hire this person" by somebody who do know you.

[retroafroman]

Which again, circles back to reputation building. Somebody, as you say, has to be impressed/like you enough to make the effort of pushing your information through the ranks to get hired. If you know the person from some other context, it's possible. If you're another resume from the stack, it's much more difficult to get that attention from anyone-HR, engineers, managers-in the company.

[wladimir]

There's many ways of getting attention of people within a company than piling your resume on the stack;

- talking at tech conferences / local user group (as the OP noted)

- contributing to open source projects

- keeping an interesting blog about a technical topic

and so on...