Serializing data for IPC is often undesirable (copies kill) which leads to multi process shared memory. Sharing memory across process boundaries safely is a pro

Serializing data for IPC is often undesirable (copies kill) which leads to multi process shared memory. Sharing memory across process boundaries safely is a problem you avoid entirely with threading. You still need to lock your data (or use immutable data), but the machinery is built into your implementation (and hopefully trustworthy).