Yeah like Zaphid is saying, I wasn't talking about stacking at all, even though 2 small camps should be able to kill one creep wave, barely, depends on how the targetting goes and what type of creeps you have(healing priest for example is pretty bad ass and so is the slowing ghost if it's not targetted by the creeps right away). But you should be double pulling to a hard camp. As I said though it's harder to deny xp since for example you can be sitting down the river behind the pull(on both dire and radiant but on dire side you can just stand at your tower for even more safety) and still get some xp, mind you only the neutrals xp(which is lower in 6.79 for most packs) and it's split between you and the 2 enemy supports so it's fairly weak. Assuming you're being sufficently zoned though it's entirely doable still. The first camp doesn't really matter and didn't really matter before, stacking was less efficient than double pulling in terms of xp/gold gained so it wasn't how you should have been doing pulls.
As I just pointed out however, the change to shared xp thing only works on neutrals, not lane creeps, so if the enemy denies a full creep wave with a double pull, even if you can leech a hard camp xp split between 3 people, that's still way way way less than what you'd get from not pulling. Better than 0, but still fairly bad. The change to the meeting point of the creeps is more important imo, especially the way it was terribly implemented, since the easy lane creeps get a fairly big movespeed buff for a short duration instead of a constant movespeed buff or a delayed spawn time, which means they're fairly hard to block properly(they move at like 400movespeed or some shit) while it's very easy to block the hard lane creeps, so the first wave will tend to be within tower range if you block it even if the enemy tries to block, and that guarantees a good sum of xp.