It probably suffers from the usual problem: people want to work at a place that is too good for them (whatever that actually means) and companies want to hire people that are too good for them (again, whatever that means).
Most mediocre devs overestimate their abilities - while many of the truely top devs severely under estimate themselves.
The recruitment process/chain at many companies severely overestimates their desirability as an employer ("If selected, you'll be given the privilege of working at this traditional corporate bank, working on 6 year old Windows desktop development machines, under overpaid architecture astronauts who's suits cost more than your weekly take-home, on strictly waterfall projects. But we'll still expect you to be in the office at 9am for the mandatory "Agile Standup"!!!)