Why can't Google create monopolies anymore?
Google in fields it has monopolised since 2000's to early 2010's is impossible to be dethroned (android, search, ads). Sure they had multiple failed products in this period too, like the google glasses or google+, but now it feels they storm a field become top 3 - 5 and just keep that position (fitbit, gemini, pixel).
Android and Youtube were acquired by Google
Once you’re big you are not hungry anymore and you have something to loose, hence you face a fundamental choice either you risk to win, or you play safe to not loose what you’ve got.
Most gigants choose the second obviously. People capable and willing to risk leave the ship. Best choice you are left with is to buy promising startups and try your best not to ruin them. And this is what they do.