I suppose the value is that you don't have to rewrite your application logic multiple times. That takes time even if you're fluent in all languages. It is also a duplicatio which increases the risk of later bugs due to not doing all changes in all copies.

Exactly - and as a after work only developer, the less I have to do over, the less I have to consult the docs, the more comfortable I am with a single tool, the more productive I become.