Well, if we represented objects with a blob of bytes, we would have to implement our own garbage collector and manage our own heap, as object references would just be a pointer that points into an array somewhere.

For interop with JavaScript, there's a usability difference between a JavaScript object and a blob of bytes, although that could be overcome with an object "mirror" that proxies operations appropriately.

Our approach was to leverage the existing GC and language features that browsers already have.