"all respects" is wrong. It also makes it so the proprietary developer can't say "here is a new version, but you must agree to some very nasty license terms, or accept some malicious feature along with it." NOT having a capability does have advantages, a physical book is impossible to be remotely deleted out of existence by DRM, but sure, you can't tinker with the software.

edit: yes, I understand in that the case of sticking the exact same software in a rom vs a read-write memory hurts the ability of a user reverse engineering it, which could ironically decrease user freedom over time. Calling this out for FSF to address is a good thing.