I think there is a big difference: the original hardware, the “emulator” was in the CPU microcode - so very close to bare metal, and was narrowly targeted to only do what it needed to do.
Compare that to a software emulator running under a commodity general-purpose operating system-it is a lot further from the bare metal, once you consider all the layers in-between (the OS kernel, libc, etc), the trusted computing base is a lot larger: its size has grown dramatically, being general-purpose includes lots of features the emulator doesn’t need or use - so from a security viewpoint, this is in some respects a step backwards - even though made necessary by economics, and simultaneously has some practical security benefits - although the general purpose OS may be theoretically worse from a security perspective, it receives huge amounts of attention, which helps keep it secure; a rarely used proprietary platform, whatever its theoretical advantages, doesn’t receive the same attention, making it more likely vulnerabilities may lurk undiscovered
Compare that to a software emulator running under a commodity general-purpose operating system-it is a lot further from the bare metal, once you consider all the layers in-between (the OS kernel, libc, etc), the trusted computing base is a lot larger: its size has grown dramatically, being general-purpose includes lots of features the emulator doesn’t need or use - so from a security viewpoint, this is in some respects a step backwards - even though made necessary by economics, and simultaneously has some practical security benefits - although the general purpose OS may be theoretically worse from a security perspective, it receives huge amounts of attention, which helps keep it secure; a rarely used proprietary platform, whatever its theoretical advantages, doesn’t receive the same attention, making it more likely vulnerabilities may lurk undiscovered