Fairly simple question. Nintendo games target mostly casuals and kids. The target aren't like us - they don't keep up with release dates which is why not all Nintendo games sales are front-loaded.
The other reason is that Nintendo systems suffer from long droughts which means that there isn't many options for people to choose from. It's easier for someone to buy 1 game from a selection of 1 than 1 game from a selection of 5.







