It changes at least one thing; now there is Google1 and Google2 and FB1 and FB2 and they offer the same services to different prices.

Now the consumer can chose between more competitors.

Almost every item you buy online has some Google 'tax' baked in. That alone isn't a problem, but since Google controls almost the entire ad market, there isn't any competition pushing that tax down. Notice the similarity to the App Store arguments?

If Google and YouTube were split up, I could see a future where both start competing for text and video search against each other. This competition would drive down ad rates across both platforms. It would also allow space for other competitors to come in.