Ask HN: How job, job title, qualification gets decided and by whom??

[4010dell]

Technologies / industries are changing. New jobs are being created in fields, which themselves weren't there few years back.

I am curious to know how these come into being, example Data scientist, crypto engineer, happiness ninja ,growth engineer, data specialist, data evangilist, Facebook hiring people to monitor Facebook post , Google hiring people to demonitize video etc.