I always thought JSONB is a great use case for client-specific customizations. For example - a CRM application where you have structured DB tables like "account", "opportunity", etc. but then a client-specific table might be "cohort" that is linked to "account" and has fields "cohort size", "cohort name", etc. You just chuck the cohort table in JSONB and now the company who uses the CRM that has the custom cohort table can change that table without creating/migrating your RDMS table structure.

Curious what other people think here?