I actually think they get promoted for shipping something exceedingly complex and challenging that still barely works. It doesn't matter if a much simpler, robust solution was passed over.

There are costs to firing people (morale, hiring overhead, other risks etc) so often they are kept around for a couple years on the hope that they will somehow improve.

0.1 devs are actually fine, they don’t really exist unless they stare at YouTube for 36 hours each week. Usually when incompetent devs start to do something the result turns negative quite quickly.