How is an increased marketing budget and selling tips going to boost sales? I would have thought that was self explanatory.
If you’re asking how an author free free day is going to boost sales, it isn’t. That’s why they’re doing the above instead. But not everything Envato does has to boost sales. The ability for you to ask how it will boost sales in a public forum doesn’t directly boost sales, but it’s a feature that was added which most find a welcome addition.