On the contrary, this decision was solely motivated by the desire to reduce fragmentation. The interfaces libstd provides can work under almost any runtime, and

On the contrary, this decision was solely motivated by the desire to reduce fragmentation. The interfaces libstd provides can work under almost any runtime, and (mostly, but definitely in safe code) don't leak implementation details. Needing a different standard library just to have a different runtime model is unacceptable. A lot of work has gone and is going into ensuring that we do not fragment. We know that fragmentation will kill us.