This happens a lot: I apply for a job and they ask for my complete address. Why? I would understand if they just want to know what city/town I'm in: That has bearing on how easily I can get to the office.
But why do they need to know my street address?
The only thing I can think: Indeed/LinkedIn/take-your-pick is building a profile of me based on this info, using my street as a proxy for my income, credit score, or, ultimately, for my social class.
From now on, when they ask me, I'm just going to put a rich person's address. For this one I used a Brooklyn townhouse where Maggie Gyllenhaal and one of the Saarsgaards lives.
That "if" at the beginning of your second sentence is doing a lot of heavy lifting. OPs whole point is why they need this before they hire them. Of course they'll need it after they're hired, no one is questioning that, so your comment is irrelevant