Google+ was started in 2010, so Google didn’t “fore”see the problem as much as “see”. I think I banged into the 1500 (1600?) FB friend cap in 2008 or 2009 from the rampant friending, and already started reducing the number and openness of my posts once older and younger relatives started joining in 2006/7ish. The timeline redesign did pour gas on the fire, but the issue of unbridled friending was noticeable far sooner to users and observers.