Good PMs should be servant leaders, doing whatever it takes to ensure their team can have maximum impact and ownership. A big part of that is identifying new opportunities, both within the org and outside of it, and empowering engineers and designers to own what they are working on.
Tech companies need people with very clear product visions that inspire their troops to build something excellent, even when those same troops are having their own opinions overridden by those of the visionary. Those people are usually CEOs and often but not always former engineers themselves. It's very hard to create a coherent, interestingly new product when you can't impose your will on a team because invariably to be new or innovative you must be controversial, and it's hard for non-CEOs to manage that internal controversy.