Millennials get a triple threat. (1) Their parents are Boomers, who grew up sheltered and overprivileged. Any millennial failing reflects their failures or, more accurately, the failures of their peers... and boomers are all about slagging their peers. (2) GenXers watched millennials grow up with the attention and privilege that they themselves lacked so their sympathies are minimal at best. Intellectually, a GenXer can observe that millennials came of age during a recession and have fewer opportunities than any recent cohort before them. Emotionally, they're the entitled little shits that got participation trophies while the Y was closing to make room for another fucking build-a-bear workshop so fuck them. (3) Any job that might have been available to a GenXer when a boomer retired stayed with the boomer when his retirement was wiped out by the recession. So the boomer is in the GenXer's job, the GenXer is in the millenial's job, and the millennial is not only fucked, he's depreciating the workplace my "disintermediating" someone else's career.

It's a pretty simple calculus - there are three generations walking the workforce right now. One of them didn't grab the hot potato. The dynamics behind this are complex and nuanced but nobody does complexity and nuance in a listicle or Vox video. So the spoonfed answer must, necessarily, be "those darn kids."