They are not optimized for what you enjoy, or even want.
A passable analogy: you buy a car and get hassled, often hard-sold for a pre-paid maintenance package, tire insurance, financing insurance, undercoating, bla bla. You don't want any of it but it's what they push the hardest.
Is it? This is how any (public) company works - they will do whatever it takes to make the shareholder return the highest. This inherently disregards what's best for the "customer." Any beliefs contrary to this is a naive belief that doing what the customer wants == the most revenue, e.g. "the customer is always right."
Maybe in some fields, but definitely not in circumstances like this where the "customer" is the product (or more accurately - the advertisers are the real customers).
By extension, "companies don't always do what's best for their customers" also applies to their employees, maybe even more so. I'm very certain that the largest US companies would kill their own employees if it was legal and resulted in the most cost savings/profit for them.
A passable analogy: you buy a car and get hassled, often hard-sold for a pre-paid maintenance package, tire insurance, financing insurance, undercoating, bla bla. You don't want any of it but it's what they push the hardest.