if it wasn't for X we wouldn't have Y

What's the name for this fallacy?

"If it wasn't for X we wouldn't have Y" - it basically states that the single possible origin of Y is X, for example "If it wasn't for Edison we wouldn't have the light bulb." or "If company X didn't exist we couldn't buy the product Y they currently sell" etc. I'd expect the fallacy name to be something like "single possible origin".

I believe it's an instance of non sequitur (because a reason why this would follow is never given), but I think this fallacy is so prevalent in this form it needs its own name :) Also there is some widespread quirk in human reasoning that makes people think the only possible way how things could be is the status quo and no two different causes can have similar effects.

I think you might be able to force fit a fallacy in here somewhere, or maybe even find one that fits nicely for specific claims. But for the most part, these statements are true/false statements. Remember that a false statement is not necessarily a fallacy, and a true statement can still be fallacious.

"If it wasn't for Edison we wouldn't have the light bulb."

One could argue that this is factually incorrect (see the history of the light bulb). We had the light bulb before Edison; he just got the credit for commercializing it. But it depends on what exactly is meant by us "having" the light bulb (i.e., the existence of it or the commercialization of it?) What if they did mean the commercialization of the light bulb? The inference is that Edison was the only person that could have possibly commercialized it. This is a somewhat absurd position to take, especially given the technology that already existed at the time (my opinion) but I really can't see any clear fallacy.

There can also be perfectly legitimate and true statements that follow the "if it wasn't for X we wouldn't have Y" format:

"If it wasn't for my dog barking at 5am, I would have slept longer."

So it is not about the form of the argument, but the content where you may or may not be able to find a fallacy.

ABCDEFGHIJKLMNOPQRSTUVWXYZ....you know there might be something to the argument that if we didn't have x we wouldn't have y.....lol

Yes, it's called false dichotomy !