Benjamin Clayborne
Auror
The way I see it, if you aren't on all platforms that are free for you to use, why? Even if it doesn't translate to more sales, 1) You aren't losing anything, it's free and
It's only free if your time has no value. It does take a non-zero amount of time to prepare and publish your ebook for multiple markets. (Unless you go through Smashwords, as I understand it, but even then there's a learning curve, and one might have other reasons for avoiding Smashwords.)
Not that it's not worth it, but the cost of publishing to additional platforms is not zero.