Except half of the time the invade is happening because a laner (namely, the one who isn't responding to the invade) is already getting destroyed in lane (often due to a counter-pick, or if not even a champion disparity at levels 1-2).
I've had a fair share of games where I'm fighting a top laner with ignite (I have TP) and it's a Pantheon or Renekton or some other top lane champion that just destroys you at level 1 and/or 2. My job is not to die in lane. What should be happening is my jungler should have the ability to see that I'm getting destroyed in lane at this critical early point and instead of trying to do a full clear he should do gromp/krugs in to double buffs and come straight to my lane at level 3. The enemy laner is very aggressively pushed so it's the perfect opportunity for him to gank! We should both know not to go too hard for a kill (as we'll lose 2 to a countergank) but the purpose of his gank is still twofold:
- Get some decent damage on my lane opponent so their champion's early-game advantage is now largely negated and I can keep up farming
- Avoid early jungling at low health where you're susceptible to an invade
What often ends up happening in these cases, though, is the jungler doesn't pay attention to the map (which is a huge no-no, you have no lane opponent so while you're clearing your camps you should constantly be checking out the lanes to see if someone needs help or if a gank will be available) and instead clears his whole half-jungle. He proceeds to the other half at level 3 and does a small camp. He's now done 4 camps, is level 3 (40% to 4) and is low health (some junglers won't even need the small camp to get that low, they go straight for the other buff and will get killed as they're finishing that camp).
My lane opponent is now level 3 at full health. I'm level 2 at 55% health and have 6 minions pushed under my turret. This is the point where the jungler SHOULD have been approaching my lane, to initiate a gank after I kill 5 of those 6 minions and to negate my lane opponent's advantage so I can outscale his cheesy early-game champion (recall, I have TP and he has ignite, I'm going to be much more useful late game). Instead what happens is I can't respond to the invade because my lane opponent is already responding to help his jungler invade (because obviously his jungler knows they're invading before we do) and if I try to follow in to the jungle I'm just going to die and miss that wave of creeps (plus the next wave while dead) and I'll be down level 5 to level 2 or something ridiculous and feed all game...
So, yea. If you're in a jungle matchup where the enemy jungler can invade you and your allied laner is on a weaker early champion than their lane opponent, it's your own fault if you got invaded and died. You played it wrong. You should have done small camp to double buffs to ganking the lane. Or at least paid enough attention to see that it was necessary (if your allied laner is winning the lane you can resume small camps instead). A gank doesn't always need a kill to be a useful gank.
The thing most junglers don't realize is most opponents KNOW an invade is happening before your allies do. They know to push in their lane in order to make their lane opponent be behind in levels and need to sacrifice xp + gold in order to respond to an invade (plus your lane opponent is pushed far enough to respond as will and kill them most of the time). Sure, if the enemy Shaco/Lee Sin tries to cheese invade at level 2 and nothing has happened in lane yet the two nearby lanes can respond and secure a first blood. Most of the time invades don't work like that though. I've never seen players not respond to such invades unless the allied jungler was stupid enough to let himself get low enough in the early clear that the enemy jungler one-shots him (I'm not sacrificing a wave of xp and gold to try to find the enemy jungler that just killed my jungler, has more than a full level on me, and is a strong early fighter, in hopes of getting a revenge kill). Junglers have wards too :P
