We should acknowledge the second edge of this sword. When a company invests in its employees' networks, it not only expands its ability to recruit more people directly, it also expands its employees' ability to find new jobs.
This may still be a net win for everyone, but it's complicated. Imagine you run a company and have identified a few bad employees. Surely you should not reward them by sending them to conferences, right? But wait, maybe you should, because then not only might they spend time learning, recruiting, and doing other things that might be more productive for your company than whatever they're currently screwing up, but they might also find a new job which is both better for them and solves your problem of how to get rid of bad employees without undue liability.
So send your best, most loyal, most enthusiastic employees out into the world to meet other people and spread the word about your company. And send your worst ones too!
If you can identify legitimately bad employees, fire them; they are not just a waste of money but an anchor around the neck of the employees who aren't bad.
Of course, this assumes a lot of things such as that you have USA/California style "at will" employment, you are capable of determining that the employee(s) in question are legitimately bad and not just hamstrung by stupid process or demoralized due to reasons you could reasonably fix, etc.
This may still be a net win for everyone, but it's complicated. Imagine you run a company and have identified a few bad employees. Surely you should not reward them by sending them to conferences, right? But wait, maybe you should, because then not only might they spend time learning, recruiting, and doing other things that might be more productive for your company than whatever they're currently screwing up, but they might also find a new job which is both better for them and solves your problem of how to get rid of bad employees without undue liability.
So send your best, most loyal, most enthusiastic employees out into the world to meet other people and spread the word about your company. And send your worst ones too!