I think my point on complexity probably stands. At early days, people were creating products from ground up. Now it's more incremental. At early days 100M might have meant doubling the revenue, but now, it's a mere fraction.

You can shave off latency and 1% improvement could result in 0.1% revenue gain (made up numbers).

You can improve relevancy of the ads by 1% and contribute to revenue similar amounts.

It's not really super hard.