No, its not. With open source software you, a regular person, can feasibly get a change included into the code base. That is NOT true with an open standard. You, or more accurately a very large and powerful company you work with or for, have to have significant pull to even hope to get a change in. Even then, those changes take a lot of time to proliferate.
With open source code that change can happen as soon as you write it, you don’t even have to wait for the maintainer to merge it; just fork the software. You can’t really “fork” Vulkan as a normal dev; no one will follow your spec. You don’t have enough pull as a single dev to get billion dollar companies to follow it. But you can relatively easily get those same companies to use your fork of an open source software.