I usually explain this one in terms of multiple projects: Project A uses postgres-11, Project B uses postgres-12, Project C uses porgres-11 with postgis and als

I usually explain this one in terms of multiple projects: Project A uses postgres-11, Project B uses postgres-12, Project C uses porgres-11 with postgis and also redis. Having them all in containers and a docker-compose.yml file makes it easier to quickly start an environment for a specific project. Ofcourse like everything in life, it's a tradeoff, and in this case we're trading in diskspace and some overhead for ease of use and portability.