My takeaway from Java serialization (which became passé) was that a schema-driven encoding that’s supported in many languages is a lot more useful.

Java serialization is passe largely because it has huge gaping holes in how one can abuse the serialization loaders to perform very unsafe security holes. And it's incredibly slow, and tied to JVMs, but sadly only really tied to JVM that have the exact same version and serialized objects, etc.. did I mention java serialization sucks? (Spoken by a true java lover that that subjected himself to serialization way more than he wanted to)