Right now you have to close WhatsApp to start a search. And then come back when you have found the answer.
There is potential for Facebook for smooth search integration in its products and take bigger piece of the search-ad pie.
Google is good to sell products that are actively searched for.
People go to Facebook when they are bored. Facebook is great to sell products to people who are bored (various forms of entertainment products and services). It's also good to sell stuff people aren't actively searching.
So, depending on the product/service you are offering you can pick a different channel to reach your customers. There's no one-size-fits-all solution.
Main problem with advertising in general is more and more people are learning it's best use is as a signal of what not to buy.
Facebook on the other hand. At least can pretend it's something a friend is recommending. Although that is transparent enough to be even worse.