Because ironically, people in software undervalue software quality itself as a moat. Look at longstanding decade-plus projects, proprietary and open source.
Some projects will never, ever catch up to competitors because of engineering labor availability, but something widely overlooked is that project philosophies can dampen marketshare goals more than just throwing more labor at a product.
You can't toss more (engineer) monkeys at a problem and expect a better solution. There will be better engineers.
In fact, I think software as a differentiator is one of the most undervalued moats we have in the industry.
As an example I was thinking about recently: the Oculus platform. This is a VR computer strapped to your face with more compute power than decades of hardware we've had in the past that could arguably be more useful today than desktop hardware of yesteryear.
Yet, if you bluetooth pair a mouse to it, mouse scrolling doesn't work. You can't build meaningful VR apps for it outside of games, or, rather the environment itself isn't conducive to attracting people who will. I can't open a terminal on it. There's no text editor on it.
You can have all the raw power in the world, and if you have no sophistication of implementation, no nuance in software, no good experience, you're a brute wielding a hammer.
Software quality is a moat.