Seriously, it's so over-the-top broken and I haven't heard anything official said on it. At this point all you can do is quit and throw yourself back in queue.
It's not **that ** broken - but it's a lot more effective at the lower you go down in skill levels.
Like in DoW2, sniper spam can be quite potent - but does have some exploitable weaknesses. You can force them off back to base with a push and build LPs behind that and secure territory (which snipers are bad at killing) and then turtle hard with Macro and Economy advantage to pump out the counters to them.
I've faced sniper spam a bit myself (even in 1v1) and, while definitely annoying and frustrating to deal with, I was able to overcome it with the aforementioned strategy.
Those are all fair points, it's definitely exacerbated by teammates not noticing their horde being ripped apart. I only ever get past it myself when my entire team has coordinated on it or I get lucky and spot them out of position. It's definitely zero fun to play against though; Eldar are supposed to be hit-and-run not hit-without-ever-running.
Its an annoying tactic in 3v3 and 2v2 but not unbeatable.
Who use this tactic tend to keep Rangers in one stack rather than spreading them.
It only takes one good distraction and one good nuker to whipe out few squads.
I finally faced this today and it was really frustrating. But after getting a nob squad out they were able to soak up all the damage really well. I also was able to get a couple good fists of gorks off that just destroyed them. But if that player was higher skilled I might of not been able to overcome it. It was really satisfying crushing them though ha.
Another helpful thread (particularly as SM) might be this one - https://community.dawnofwar.com/discussion/10688/ranger-spam-solved#latest
I've got no experience with Orks unfortunately, and in terms of an Eldar mirror it's just Ronahn / Macha-reliant (pick one or both), and who gets the better placement.
outside of being OP , this tactic is boring to play against. from the esl people beat the ranger spammers only very late in the tournement . good ones being noave and kifire. The only way they were beaten was being out cheesed. It took something more op to beat rangers for example assault space marines spam with x2 jump / true damage and listening posts everywhere and weirdboy E combined with nobs . Keep in mind vs orks the matches took over hour each and the ork player refused to commit against that tactic w.o overwhelming force because they are likely more susceptible .