Wouldn't dedicated candidates generally hit up someone on LinkedIn to get put into the backchannel? Heck, people on HN have generously offered to put me into their company backchannel, so it doesn't seem to hard to get into it if you really want it.
There are some good ways to gain that level of contact though - directly reaching out to current employees is pretty effective with very few downsides as failing to get the job means they aren't going to be your coworkers anyways. However, I think even these approaches make the process overall less fair and equitable.
However, the more you limit your hiring pool the more you're missing out on good folks and you can end up breeding a culture of nepotism within the company if you're not careful - where those folks that make it in from the outside are outside of the social group you're drawing from and end up leaving because it's cliquish.
If a good employee vouches for someone, there is big chance we will give it a try. :)
If I ever decide to go out on my own and form a startup, my co-founder will 100% be an ex-colleague. Is that fair? Dunno, but it’s the only reasonable choice IMO.
I read about people who fill out hundreds of applications and never get a response. I know it’s a numbers game, but that is absolutely wild the amount of effort people put into a strategy that clearly isn’t working.
Of course some don't answer, but it's not a big number