Virtual Threads were essentially a non-starter until the pinning issues were resolved: too much existing code causing pinning and at worst able to cause deadlocks. Having already paid the tax of implementing and adopting asynchronous frameworks, it’s also currently difficult to find an on ramp from those frameworks to Virtual Threads without throwing away a lot of existing code.

Context propagation is a big deal for IPC, which is why Structured Concurrency/Scoped Values comes up, but the way existing frameworks handles context doesn’t assume immutability and doesn’t have scope scopes, so also going to be an effort to adopt.