parents are also reluctant to let the kids experiment too much with the family computer, it's really easy to mess things up badly (even with a bootable CD)
a 'impulse buy' priced computer that's completely separate doesn't have these issues.
A lot of people got started with programming not by typing programs in from magazines, but from tweaking existing games (i.e. 'cheating')
something along the lines of a Pi is perfect for that, the worst you do is damage the OS badly enough to need to re-write the SD card.
It doesn't have to work the majority of the time, at a million units shipped already, if it only works a fraction of 1% of the time that still gets a lot of new programmers.
And I think it does wonders at changing a computer from something super special that only special people deal with into something that they aren't afraid to experiment with, even if they don't do any programming themselves.