Earlier quoted context omitted.
I honestly don't even get why reward pools are such a big deal. I do work for you, I am owed compensation based on terms we've negotiated before I started working for you. From time to time these terms will come up for renegotiation. There is no need for compensation in excess of what we've negotiated. Sure, I am not one to turn down free money, but understand that this does not affect our normal compensation discuss…
The purpose of discretionary bonuses is to address imperfect (and potentially asymmetric) information about just how much you really are worth. It can be easier to assess post-hoc. Whether it actually does this well is certainly an important question, as well as how it can be abused and how frequently that happens, but it seems remiss to rail against them without noting their intended purpose - which, in the abstract…
If I am not performing to expectations, fire me or renegotiate my salary. There are a great many ways to tune my compensation to my actual determined worth.
A discretionary bonus in this case is simply "you should take a below-market salary until we're convinced you're the real deal, and then maybe you will get the salary difference back". I'm not convinced anyone who isn't desperate will take this deal.
And having experienced the discretionary bonuses at two very large and well-known software companies, I am absolutely, completely, vehemently disinclined to ever enter into such an arrangement again.
For discretionary bonuses to make even the most remote amount of sense, it needs to offer the employee an upside for taking on the uncertainty.