Effort is a multiplier. A bad idea with a ton of effort won't go anywhere. A good idea with a little effort will succeed in a small way. But a good idea with a lot of effort... that's when things are massively successful.
It's more complicated. Sometimes a simple spin to the messaging is all that requires. Sometimes your idea can be too early and at times little late by the time you built it. It's almost like fashion - no body knows what becomes a hit, even though some popular design agencies can give some good boost to a particular trend (y-combinator).
Another analogy is viral music videos, even though some videos have all the ingredients they never take off, while others go viral. Same is sometimes with not-so talented getting popular due to various factors. Another analogy I could think would be movies or game production, no one can really know when it will go viral, but you can do some calculated risks and make sure that it will become at least a modest success. Like sequel to a hit movie or a poker/gambling games that won't go viral but can give consistent returns. That can be thought of as b2b in software markets, while b2c leans towards viral/large success stories..
Worth pointing out in a tongue-in-cheek way... Effort alone is useless, execution is what is important. One of the things you learn in an MBA program is how to tell the difference. :-)
There's no particular correlation between MERIT and success, never mind effort. My own work's increasingly based on the notion of, if you want merit/quality, come up with some way for it to survive outside of the success dynamic, then pursue that way.