Did you miss my link to the BLS data showing the difference between hiring number and job openings ?
There's plenty of empirical ways to show that unadvertised hiring occurs. Another alternative way would be simply to survey companies and employees and ask them.
The fact that unadvertised recruitment happens doesn't mean that the jobs will be available to anyone who attempts to apply via cold-calling.
A company that receives a strong recommendation for a candidate via someone they trust may well create a new role especially for that person, but obviously such a role wouldn't exist if someone unknown tried to apply speculatively.
There's plenty of empirical ways to show that unadvertised hiring occurs. Another alternative way would be simply to survey companies and employees and ask them.
The fact that unadvertised recruitment happens doesn't mean that the jobs will be available to anyone who attempts to apply via cold-calling.
A company that receives a strong recommendation for a candidate via someone they trust may well create a new role especially for that person, but obviously such a role wouldn't exist if someone unknown tried to apply speculatively.