I wouldn't call the scout rush broken, and I'd say it's easily counterable. The reason it works is because no one bothers to counter it because it's never expected. Also, this doesn't work on larger random maps where the enemy homeworld is 4+ jumps from your homeworld. It works if they're 3 jumps, but you need to find them quick.
This is counterable. My answers if you are scout rushed are this:
If you're quick enough, by selling 200 metal and buying 200 crystal right at the start, you can have:
Your mines completed
Scuttled Your Cap Factory
2 Military Labs completed
THEN you lose your constructors
Just build the third at your asteroid
Building quick enough early game makes the strat null and void. You'll still lose the constructors, but that doesn't matter. The trade off here is you make NO fleet at the beginning. I mean no fleet, except for the 3 starting scouts. You get the cap and let it go and colonize on it's own.
Ok, so let's say you didn't build quick enough early. Let's say you have the first military lab started and all of a sudden bam, 4-8 scouts show up.
If you were going sova rush or picked the carrier cap, the fighters can take out the scouts, but it's rare for someone to pick the carrier, so let's say you don't have that.
If you were quick enough, you should have colonized or at least be close to getting your asteroid. If there is another asteroid or a lightly defended terran/desert, you can pretty much ignore the scouts. You'll get the 1 lab on your homeworld and can make your labs on other planets.
Sometimes that isn't an option though. You can make turrets to counter scouts. When the scouts show up (and you should spot the enemy scouts coming if you are watching your own scouts), have 1-4 turrets turtled together around your frig factory, and have your constructors there. (More turrets the better, again, you'll have more if you spot this early, seeing as there's nothing else to do early game, you should watch for this).
That's the "O shit, i've been scout rushed answer".
I say the best answer to counter this is to build first, get a fleet second. I have never been scout rushed, so I can't say this necessarilly works, but that's my assumption, and that's how I play anyway. It doesn't cripple you early. If anything, the only drawback to building 2 military labs early is that you can't colonize an ice or lava early, or if you build 2 econ labs you can't build a good fleet early.
If you're going econ build, you don't need to worry for you can just make the lights to help your cap and build at new captured worlds (preferably a desert or another terran)