The job-listing sites are filled with ads looking for Drupal developers who have years of experience building Drupal sites, and are experts in object-oriented PHP programming, and are skilled with React and headless development, and are experts in SASS and Gulp and the rest of the front-end toolchain, and can create documentation for executives, and can design information architectures and user interfaces, and train the editorial staff, and optimize the SEO and e-commerce conversions, and...you get the idea.
You don't need one person who can do everything. Design your workflow so that people can focus on the things they're best at, and spread the work around. Then, when there doesn't happen to be a superhero around, you can still keep things working as they're supposed to. The bridge doesn't have to fall down.