I think if you're a grown up, you shouldn't have to worry about things like how to not stomp newbies.
There's a difference between losing and getting stomped. Getting stomped is seldom going to be enjoyable for anyone and is unlikely to do much to encourage someone to try the game again let alone buy it.
So the goal is to help them become comfortable with the game, and enjoy playing it.
Yes but, we're acting like there is some kind of barrier to that when really there isn't. Any normal adult will recognize the social implications of gaming and act accordingly. If they can't or won't, then there is hardly a discussion since we as the motivators for change will simply move on.