Saw it happening a few times in my 12 year of industry. I suppose it's specifically common in companies that use social media (and other media) presence as a recruitment boosting tool.

Twice the "leader" of the "Totally Amazing Success" left the company to "be totally amazing" somewhere else. In both cases the team was made mostly of very young engineers, the level of amazingness was strongly overestimated. It was also declared very early, before the "novelty" of the "new thing" faded, and also before the downsides appeared while maintaining the product.