Newer tech stacks might also indicate chasing the newest/hottest thing without regards to long-term sustainability of the platform, however. You don't always want to be bleeding edge, as bleeding edge can easily be dead five years from now, whereas if you stick with a "boring" mainstream technology it'll still be around in five years.

True. But the enterprise shops I've seen tend to make the "not modern enough" error 20x more often than the "too modern" error.