I tell them the number up front. Because I'm not spending a week in their interview loop to find out they're going to offer me 30% less than my current job. Benefits are never a decider, and equity is a lottery ticket.
What's surprised me is that most of the younger coworkers I've had, having grown up largely through boom times, absolutely believe that this equity has tremendous value. I've had multiple younger coworkers talk about how excited they are to have so much equity in companies that have no visible path to a liquidity event.
Yes, it's a polite way to brush off the question. But the end result is the same. A job offer way lower than what you're making, and now they have $20K in a bucket to go a little higher when you try to negotiate.
The argument is “we have a competitive benefits package”. Yeah, so does everyone else.