Pedantically, the standard library (strings, basic networking, containers/collections, etc.) is already well defined and quite small. The Rust Platform idea see

Pedantically, the standard library (strings, basic networking, containers/collections, etc.) is already well defined and quite small. The Rust Platform idea seems more aimed at providing access to curated, stabilized versions of community-developed librares for common higher-level tasks (async I/O, serialization/deserialization, etc.). Personally, I think that letting users (especially beginners) opt in to a larger set of starting libraries could be very beneficial for adoption.