I don't really keep track of all the exposure I get in the eShop anymore, but I've certainly seen some good promotion from Nintendo for which I'm really grateful.
However, whatever way people want to rationalize the success doesn't really matter. The main reason for me to share my experience is to inform and shed some light the market space that could hopefully be useful to other devs. If you can explain that easily why I'm having more success on one platform over the other that's fine, and I don't necessarily disagree with your conclusion, but that doesn't mean the exact same logic couldn't apply to more games and be valuable info for other devs.
There is still room for more many indies on the eShop before it gets nearly as saturated as Steam (or the app stores), and it's easier to release on 3DS than Steam. I'm not claiming that eShop is a bigger market than the others. There's certainly many way more successful games out there on all the markets, while I think I'm in the top 20 in most regions for eShop. But it can be a great market for indies and I don't think I've done anything special that couldn't apply to other devs.
Sorry for the rant. I'm a bit drunk and get a bit annoyed at quick, seemingly dismissive remarks (I'm not really sure if that's how you intended it).
Don't have a linux version, sorry