Is this just a shift from "startup mode" to "mature business mode" - the startup junkies are moving onto new ventures and being replaced with employees who pref

Is this just a shift from "startup mode" to "mature business mode" - the startup junkies are moving onto new ventures and being replaced with employees who prefer to work for a more stable company? Could it indicate that Twitter's hardest engineering problems have been solved and they plan on keeping the service lean and simple, so there's not as much need for a large team of people to build new features? This would make a nice change from Facebook and Google, which seem to be straining under the weight of feature-bloat. Or, is it symptomatic of Twitter hitting a dead end and senior staff deciding there's no money/business there? This is all speculation, would appreciate any opinion or insight. Hypothetically, if you were offered a position at Twitter right now, would you take it?