I'm curious though... aside from knowing the sales of a game for the sake of it, is there anyway this information can be helpful in the development of one's own game?
I'd say probably not. Clone games are rarely great games, like with your Flappy example. You have to offer your own spin on something
You could definitely learn from the failings of a game similar to yours, though. If you wanted to throw your hat into the pool of 2D crafting games like Terraria and Starbound, there is a lot you could learn from how they designed their games, and what people didn't like e.g Starbound was criticized for being released too early and having to be save wiped per update. Perhaps in that sense, you could find games that sold well within your target genre / style, and use them as a basis for inspiration.