What's riot going to do about that? Them not having a jungler is usually either because two people in your blind on the enemy team "called" top and autolocked or something whereas neither conceded. You don't have to cs well, just use the experience to learn how to position yourself well to get exp. As long as you can semi safely farm under tower- chances are the two will fight for cs and shove it in. In the worst case, you end lane phase with ~20 cs but hopefully not too far behind in level, where your jungler had free farm of their camps and the other lanes had no pressure whatsoever from a jungle. It's a blessing when this happens, you just have to learn how to work with it.
Edit: forgot my other reason, otherwise chances are as its a pre-thirty game, theres a chance people didn't have the runes or champs to jungle properly and rather than have a poor experience ended up top together.