I've never heard this said this way before, can't say I'm a fan of the wording. I'm not grateful for alcoholism in any way, I'd rid the world of addition if I could.
I do have gratitude that my RAH's issues brought me to my own recovery & allowed me to work through my ACoA issues that existed long before my marriage ever did. I may have never really understood how much I needed it or taken the steps to become healthier. *I* like myself better as a recovering person.
I am grateful that for some strange reason, addiction allows to address the underlying root issues more honestly. Like, RAH would never accept that his FOO issues existed or that they caused him pain on it's own..... but through the lens of his own recovery he was able to accept it & work on fixing it.