In 6th, without touching forgeworld, and using Space Marines as allies, I can field 6 unsquadroned Russes, or 18 squadroned, plus some predator tanks. My infantry in a list like this becomes a squad of tactical marines, and either two vet squads, a platoon and vet squad, or two platoons.
It's an impressive list of stuff but you're surely talking about 2500 points region, where cramming huge armies onto standard 6x4 tables with no terrain is hardly a tactical game, normally players talking about 'alpha strike' to convince people it takes skill to try and get first turn and then shoot their guns. Your example is almost akin to apocalypse really.
In more competitive gaming environments heavy gun line lists will probably find things harder, playing with a sensible amount of terrain to stop every objective being in LOS of both armies makes a difference for example. While a squadron of three leman russ looks impressive it's generally going to be overkill and thus inefficient against many targets.
I was saying I could, as an example. I prefer a far more balanced gunline, which by the way in a competitive environment is doing just fine. Since 6th edition, I've lost once: Armies played: Grey Knight 4 times, this is where my one loss was, Tyranid once, Orks twice, Guard Once, SM Vanilla once, Blood Angels six times. If through my Eldar list, there are a little more. This is not me tooted my horn, merely preparing the grounds for my next statement.
Anyone who thinks there is no skill in setting up a heavy hitting gunline is quite frankly a little out of touch. Yes first turn is important for such an army, and if I get first turn, stuff goes REALLY well for my army, however anyone who has played a list like this knows that:
A: You can not depend on going first.
B: More so in 5th, then 6th, you can not depend on having anyone to shoot at on turn 1.
C: You will every so often have to play a game where capturing objectives is required.
No good good line is truly static, it has mobile elements that will be utilized to funnel forces to more desirable fire lines. It has flexibility and layered plans. The advice I always give to new guard players: Don't panic and stay flexible. The don't panic is obvious, the stay flexible is not so much. For example, Hymirl, you looked at that tank heavy list and assumed there was only one viable tactic. I don't get turn one with that list... so since I know this in deployment, I deploy two lines of tanks with my infantry in the middle, and make sure no tanks LOS is blocked completely. I then do a simple line advance into my enemy, or if they are assaulting, let them come at me. At the last possible moment, hoping for good luck on lumbering behemoth, and depending on Chimeras and predators, tank shock the enemy line, scattering it, and breaking an attack. Hellhounds open fire to continue to ruin the days of the enemy line, as my second tank line had moved forward to no shield my footsloggers, who are now firing into your guys as well.
As long as you see a Leman Russ as just a big gun, you will never understand how a Leman Russ works.
Does the new fragility of vehicles make the tactic above worse? A little.. in my opinion it makes it fair.
In the end, I like a more mixed balanced list though because of the whole flexibility thing.