Well, I’m not sure why we use “utility”—that seems like a profound question. But that’s the criterion we’ve used to choose our concepts practically forever, so why make the exception for this one concept?
I have to hand it to you. It's clear that you're adept at creating confusion around ideas by "just asking questions", and creating cohesion around fuzzy concepts by stating opinions as facts. I've participated in too many of these "debates" to know where this is headed. If you genuinely want educate yourself on these topics, there are resources to do so. I encourage you to seek these out.
When you argue like this, it betrays your inability to defend your position or even admit as much. And anyway, this isn't a high school debate with winners and losers, it's about understanding and advancing. The defensiveness is unnecessary.