I don't think the reason I'm about to discuss is behind all of these stories, but I think it is a persistent force in our industry.

I am somewhat convinced that a not-insignificant portion of engineers is under-employed in an intellectual sense. When $BIGCO announces the release of a new tool that supposedly helps with their planet-scale needs, the engineer just lights up at the thought of needing to dig into a new challenge. (The impulse to grow is well and good!) It also helps that places like HN buzz with new tools, it is good resume material, and a vague feeling of not being left behind if said thing takes off.

The real fix is to get away from domains/companies that bore you in this way, but it is not an easy realization. There are a ton of interesting problem domains out there! I did this and am much happier with my career.