I try to put myself in the company's shoes:
Employee: Please pay me more.
Company: Why?
Employee: If you don't then I will be able to find a more
lucrative/satisfactory position elsewhere.
At this point in the conversation, the company has only a couple of possible responses:
1. You're free to do so. I'm not increasing your pay.
2. Ok. I'll take your word for it. Here's a raise.
3. Prove it, and I'll give you a raise.
#1 is the only option if the company is strapped for cash and the best option when the employee's net value is low.
#2 can be a good choice if you have a very good sense of the job market and what makes a competitive compensation package OR if the employee's net value is high and an equally good substitute will be difficult to find.
In all other situations, #3 does seem the most sensible and least risky.
If a company is inclined to #2, they can and probably should award the raise preemptively, before it has been asked for.
Now, as an employee, if I suppose the company has thought all of this through, and they haven't preempted me with an offer of a raise, then I can infer that #2 is not among the possibilities. So I probably don't even need to ask for a raise. I should probably just look for other jobs and then when I get an offer I can find out if the company is going to take option 1 or option 3.
As a big company, such as a Fortune 500, often a manager will want badly to retain an employee and would happily go for #2, even preemptively. But if the senior management (who never even sees that employee) does not share the manager's assessment of the employee's value or the manager's familiarity with the job market for that role, then they will not allow it.
I've seen all of these cases occur. Happily, my current employer is happy to pursue option #2 for high-performing employees.