They're explaining the technology they're using, which makes it sound like they don't know who they're marketing to. The average person isn't going to care about the stack, and the people who do care might not see the point in paying the price of a Raspberry Pi every month to run a Raspberry Pi.

Then again, if it saves a lot of people just a little bit of trouble, there's a lot of potential there. There's a lot of services that are like "dude I could have made that in a week!" but humans are lazy, and developers seem to be especially lazy, and many will happily pay for a pre-configured / hosted solution that "just works". :)