How is the candidate not at a loss?

Under the current system, a candidate can ask any number of questions about the company, their culture, their technology, and other things that are of extreme importance to the candidate in deciding which opportunities to pursue.

Under your system, none of this can be meaningfully answered except the "brochure" facts that are trivial to discover anyways.

Under the current system, a candidate immediately meets with a member of the company.

Under your system, he/she will meet the employer "eventually".

Everything about this system is a net negative compared to the status quo, for the candidate.

In the current employment climate for (good) software engineers, where demand massively outstrips supply, I simply do not see a system that penalizes candidates going anywhere. I really hate whipping this card out, but the last two times I've been actively seeking a job I've had no less than a dozen companies respond positively within a single day. I would be severely disinclined to do anything through an intermediary.

This goes double if I'm only passively looking. I'm not looking to jump ship, so I have zero desire to spin my wheels on opportunities without any information on whether this is interesting to me or not.

The climate favors the candidate, not the employer, unless the employer is exceptional. IMO your idea can only be viable if it brings something to the table for both sides.