By my definition 10x/100x dev means a person who makes decision which require 100x less resources to execute to achieve the same goal. For example, one can build clean, maintainable and monitored codebase/infra, which will support business goals and rapid evolution in long term, while some group of mediocre engineers can build overcomplicated system, over-polluted by bugs and technical debt, which will be significant liability rather than useful asset.