Continuing with this analogy, that once all the building block are in place (GC, threads etc.), it would be time for building a WebAssembly-native programming language.
The wasm security model is a lot more complex than your CPU's. It was never a virtual CPI architecture.
And because it's not a virtual CPU architecture, it need those extra complexities. Your CPU is designed for running high-level languages without any of those extra features, but wasm can't do it (well enough).
https://www.destroyallsoftware.com/talks/the-birth-and-death...
Here's an example:
https://developer.arm.com/documentation/ddi0439/b/Memory-Pro...
More complex designs tend to go for a full-blown MMU, and I wonder if the presence of such a feature would be warranted when you could go for either full-blown process isolation (which afaik is not that expensive on modern CPUs), or just go with static and dynamic checks (basically and if statement that checks if the address is valid, which can be optimized away like 90% of the time, when iterating through known arrays etc.)
The issue with if statements are that the stats/bits branch predictors use are a finite resource. You really need these checks to be inlined as well because otherwise you'll thrash the instruction cache. If it just had some special register with an interrupt, the CPU could just always assume the index is valid for the purposes of speculative execution and branch prediction.
That's why they are making it more complex.