The key things were:
For a brutally simplified example; country A has stealth fighters equipped with GPS guided bombs (which also requires a GPS network), while country B has normal jet fighters with laser guided bombs. If they go to war, not only can country A sneak past country B's radars and destroy energy, communication, industrial, and transport infrastructure, but it can also destroy country B's fighters before they even leave their hangars. Country B just doesn't have access to this strategy because of its lack of stealth technology. If they tried it, country A would have plenty of warning to get their jets up and running in order to set up a defense.
Well, this example is not "brutally simplified". I'm not a big expert in aviation but, again, from what I read stealth fighters aren't such a great advantage as you think:
1) They're terribly expensive. This mean you can not use them as usual front aviation, but only for precise strikes here and there. To do that, you must be sure they will stay invisible, but...
2) Actually, they're not invisible, Russian air-defence perfectly sees them (or, to be exact, their traces). And as soon as they were noticed, they becoming the few-billion-worth targets.
In short, this may be a decisive advantage in some "peacekeeping mission" against some small country, but doesn't make much sense in large scale war of equals.
1) This may have been true for the first stealth bombers, but not today. Today they are expensive, but not terribly expensive. Look at the F-35; it's a multi-role stealth fighter family, and the whole point of building it was to have a stealth fighter produced in massive numbers for the US military (the US plans to source 2443 F35s eventually). With these numbers, you can enjoy the advantages of stealth technology without worrying about the price of losing one here and there. Let's also not forget that stealth fighters aren't flying bricks either, they're deadly fighter jets in their own right. The F-22 is considered to be one of, if not the deadliest fighter in the world. Speaking of which, the US also planned to acquire 750 F-22s before the short-sighted decision (Obama's fault here) to cancel production because for some incomprehensible reason, the Americans believed there was no chance China and Russia would discover stealth technology this century. With the F35, it's clear that stealth fighters will form the backbone of the US air-force, so they surely will not be limited to precision strikes only. China also has the economic might build an airforce around stealth, but it's production of the J-20 is going very slowly (only 20 produced so far). Russia is clearly lagging behind in this area with only 10 prototypes built, so in Russia's case, yes, the airforce would be very hesitant to deploy the Su-57 for fear of losing it.
2) Yes and no. Stealth fighters are designed to be avoid detection in higher frequency bands. However, low frequency radars, like the OTH radar systems you talk about, have always had no trouble detecting that a stealth jet is flying around (somewhere). These radars can't pinpoint the exact location of the jet, however. Of course, this isn't nothing; once you know the jets are there, you can send your own up to chase it, or try to shoot it down. But there are two reasons why stealth still might give you an advantage; time and logistics. Depending on the range of your OTH radar, from the time you detect the jet, to the time your own jets are up in the air, the stealth jet may have already dropped its payload. Maybe it even drops its payload on the OTH radar, which given the logistics of most OTH radars, would be very easy. Russia's system is designed to be mobile, but this sacrifices range. The really long-range radars such as those Iran has built are huge installations that consume a lot of power and can't be moved around. Perfect targets for a cruise missile bombing campaign, or perhaps even electronic warfare. Stealth isn't invincible, but neither are radars.
But this brings me to the main point; who has access to such radars? Only China, Russia, the US, France, the UK, Iran, and Australia. Again this isn't really about the US vs. Russia, but more so about the US or Russia vs. a smaller military power. So yes, my simplified example is obviously false if you factor in OTH radars (that's why I said it was simplified). But the message behind the example is still true; if country B doesn't have OTH radars then the technological gap will leave it vulnerable to a stealth first-strike. The importance of technology is still there. Just look at the military and war news on here; there's a reason why countries pour billions into R&D--more than ever, technological progress is what militaries rely on to remain relevant. To tie this back to stealth, quantum radars may be on the horizon, which would make stealth obsolete. Now, the country with the quantum radar would have a massive advantage over the country without it. Same goes for ABM technology. It just seems to me that the report is incomplete without considering how advanced each military is.