> And if your theory that companies prioritizing results for profit would lose to companies that always prefer the best products, why is DuckDuckGo still in what... fourth or fifth place?
You'd need to argue that DuckDuckGo's search results are better; I don't think they are. That's what made Google first among many competing search engines, before there was even a clear business model in it. Today the incentive to outperform is bigger.
If a product Y definitely better than X comes along, and only Google Search fails to rank it higher, people will start thinking "I rather search on Bing too, as it finds better products in this category".
Maybe Play Music is the best thing. Maybe it is not. Neither of us can answer that. But if a definitively better product comes along it will have no way to make a foothold because Google is still pushing everyone to their own product, from their other product (Search), and even when people try your product, if they use Google's other products, they'll tend to stick to other Google products.
Honestly, the worst problem with companies like Google is vertical integration. The ability to provide a wide product line where you integrate best with other products your own company makes has an incredibly chilling effect on competition, and therefore, innovation.
And if your theory that companies prioritizing results for profit would lose to companies that always prefer the best products, why is DuckDuckGo still in what... fourth or fifth place?