Sorry, I won. Not just by firepower.
But having more firepower lets you win faster. Winning faster means you lose less org and suffer less losses. I'll bring this point up again in case some people were unaware. +20% attacks can mean upwards of +80% damage. Divisions of course are a balance of a combination of stats, and attacks aren't everything. But attacks are weighted pretty favourably in that balance.
Infantry that don't pierce will need double amount of Org of the tank division to stay. It is hard to do that if the Org of the tank is 50 or more.
Do you realize how easy it is to pierce these divisions? The first one you posted with the 20 infantry has all of 44 armor. You can pierce that with a 10/0 using engineers, artillery, and support AA3 and IE2 with an infantry AT upgrade. You can pierce that with AT2 and no infantry AT upgrade. The second one is a bit more ambitious with its heavy tank destroyer and ~78 armor. A 9/2 can pierce that. A 9 infantry 1 superheavy TD with +5 gun, or american HTD3 with +5 gun and TD board is going to make an absolute laughing stock of all of these space marines and even medium tank divisions up to 15/5.
These sorts of divisions are largely only good for beating up the AI, any sort of actually intelligent, rival power is going to be able to handle these space marines just fine. If beating up the AI is what you want to be good at, go right ahead, field all the space marines you want, roll around in single player and have your fun. But I honestly hope that you will understand that being good against the AI is like beating a baby in a foot race as an able bodied athlete. They can't even walk, let alone run, they have no concept of what is even happening. They were hardly competition to begin with. The purpose of this thread isn't really to debate space marines, its about doctrines and why the MA doctrine is widely regarded to be pretty bad.
By several different metrics, most of the divisions you've mentioned have been better served for their mentioned goals by either MW or SF doctrine. A lot of them probably benefit a lot from GBP too, but I'm just not as familiar with it to be able to immediately draw the comparisons off-hand. All told, there are basically only 4 advantages that mass mob has, and most of them don't even get fully utilized. The first is it is the shortest doctrine, it takes less time to fully research and get all of whatever power out of it. The second is its recovery rate, which can be pretty high but MW can rival it and while it can be useful, its use can be replaced by other means. Reinforce rate, which signal companies can largely replace, especially Soviets with NKVD focus adding another +5, or using high speed divisions. And lastly, their divisions will tend to have a bit more HP because of having a bit more infantry, which is both a blessing and a curse. Blessing, because more HP means better HP ratios, longer last-stand if you have the CP for it. Curse, because you're being forced to use the infantry, which are slow, unarmoured, and completely soft. It will also drag the averaged stats to their level which is good for org and recovery and most of the terrain mods which are generally good qualities for them, but it is bad for piercing and armor and hardness, as well as costs to field the division in terms of supply, IC, and manpower. This advantage can also be somewhat offset by leveraging more firepower or maneuver with other doctrines to not have to fight as much, and therefore not lose as much HP to worry about having to have more of it.
The cheap tank divisions will laugh if you use 20w infantry to pin them!
They can laugh all they want, they're still going to be pinned. And most likely pierced. Mission accomplished.