Rogues were doing this for a long time.
Piercing Strike.
+5 Dex +1 rogue talent +1 Expertise +3 Proficient +2 CA (most rogues should have this all, or substantially all, of the time) = +12 vs Ref at level 1. Assuming NADs are approx. level+12 = 13 Ref for most level 1 monsters, the rogue is hitting on a 2+.
The difference is that when the game first came out, the Rogues only had CA when they actually went in and flanked for the most part (and they didn't have Expertise at level 1). And since the Defender tended to position himself between the rest of the party and the monsters, that meant that the Rogue had to position himself even further behind enemy lines to get flank with the Defender.
That's +3 (CA and Expertise) of the +12 and it's also the Sneak Attack damage part of it. So sure, a 5 to hit, but doing D4+4 or so damage made up for the fact that the Rogue could hit on a 5.
I had a player play a Rogue in the Scepter Tower of Spellgard adventure two years ago and that PC was getting smacked unconscious about every other encounter because the average AC, the lower hit points and other low NADs made him extremely susceptible to any sort of focus fire.
That was part of the adventuring. Risk and reward. Reward of the best damage in the game system with the risk of being in combat with lighter defenses and hit points.
Thieves don't have that. The Thief in our current game almost never misses and infrequently gets into direct melee combat.
Reward without risk.
Rogues have a lot more of this low risk reward now due to feats like Treetop Sniper, but the original game balance of damage vs. risk is no longer a significant part of the game.
Now, Rogues and Thieves get CA almost every round which means that their to hit and hence DPR is generally higher than that of other Strikers. Because of this, the feat/item/power arms race has to swing back and give other Strikers even better feats to make up for it.