I'm not convinced that it does. I've never seen a dev comment about intending strikers to deal multiples more damage than non-strikers, and I don't see anything published that conclusively implies that intent.
The various basic striker mechanics create a fractional increase in dpr. Striker powers tend to focus on damage over effects, but it's far from unilateral. Multiattacks, minor attacks and immediate attacks can generate massive damage when combined with lots of damage boosters, but I think this is more likely a general design oversight than evidence of intent that strikers should be dealing truckloads of damage.
The problem is not that Strikers can outstrip non-strikers, its that monster HP balloons way faster than player damage can keep up without dipping into multi-attacks in some form or another. Consider the following.
At level 5, a rogue is facing a sea kraken. It has about 420 HP. Your "big" powers are going to be landing for 4d8+11, or about 30 damage on average, and that's not a totally unoptimized Rogue either. That's about 1/14 of its health. 7%. Your allies will be hitting it for around 1d8+7, or 11.5, 3~%. In a five man team with no other strikers, you will be pinging it for somewhere around half 19%, which means, not accounting for spike damage, the fight should be ten rounds. Accounting for novas, buffs, and spikes, it should be less. 5-6 rounds. Which is good for a boss fight.
Fastforward to Lolth, who has 1260~. To fight at the same speed, i.e., ten rounds without using nova powers, you need to be pumping out
126 DPR. Which means, unless you min-maxed for accuracy, you need to be throwing over 252 damage at her a round. Even if you did min-max accuracy you'de still need to be tossing 252. It's only when the party can start hitting Lolth on 10+ that that number can drop. Now, that same party that was doing 1d8+7 damage a hit in heroic? All told, in epic, unless they invested extra any reasources into damage, their only going to be doing 2d8+14. Double the damage, while the monster HP has trippled. You're other four teamates are only pulling 92 average damage, leading you, sir striker, to do
160 at-will damage to keep up the same pace. All the while, Lolth is going to be running around beating your face in. Theoretically, a really twinked controller can make up the difference by just stunning and dominating Lolth every round, but that makes the fight
beyond boring. So, strikers feel pressure to over-preform to make up for






PC damage scaling in epic. Which means fewer and fewer striker classes, and even fewer builds per class, can survive into epic without the game becoming a long, boring grind. This is he reason why I think just halving HP seems to be so effective for a lot of people, because few play on the cutting edge of optimization, which is where you need to be to keep the game balanced in epic.
By using the flurry and the revised HP scaling this allows more people to be effective with less damage focused builds, and allow way more classes to enjoy being an effective striker at the table.