Because a VC that is more concerned with the type of phone you use than your product/service/company is probably a VC you should stay away from.
Imagine explaining to investors in your VC - "You know that XYZ company that just IPO'd for several billion dollars? Yeah I passed on their series A because the founder didn't have an iPhone despite the business itself being really solid". If I was an investor in that VC I'd sue the partners into the ground over such trivial bullshit.
Yeah, but the whole point is that if it IS explicitly stated or even implied, then the whole concept of a VC's fiduciary duty to its investors gets thrown out the window because of some partner's personal biases that have no impact on a given company or product. That's unethical and dubious at best, and illegal or outright fraud at worst. All because someone didn't like that someone else was using a different kind of phone. That's nuts if you think about it.