Those were never direct competitors and never a threat to Google. Unlike easy-to-duplicate and fleeting social networking companies. Keep trying and keep in mind the DNA of Google in terms of being founded based on algorithmic technology as opposed to cut, copying and pasting text entry boxes for vicariously spying on girls (while also calling users "dumb f*cks" is much different than a core algorithmic search engine. This is evident by Google's revenue and breadth in hardware (TPUs etc) and true AI. Add the fact that Google controls more popular properties and products in terms of user adoption and revenue.
Google has never had to buy a competitor as its revenue, scientific and technology value is orders of magnitude greater than facebook et al. I'm looking for the next Google not the next facebook/myspace/snapchat/instagram.