To an extent, but if anyone suggests that it was the greatest factor, they would be putting the cart before the horse. The main factor remains the indoctrination of the German soldiery, and the subsequent reaction by the Soviet authorities. I'm going to answer your question first, then elaborate on the aforementioned indoctrination for anyone else who may read, and why it helped define the nature of Operations more so than any tactic or weapon could.

The Eastern Front saw a very odd kaleidoscope of combat tempos, that would have been nerve-wracking to any combat arm. Long treks of nothingness followed by sharp and incredibly brutal actions. This is to say nothing of the urban combat that has become the stuff of legends.

The Soviets were notorious for their incredible camouflage discipline, even by German standards, and roaring firefights would erupt seemingly out of nowhere as concealed forces emerged from a balka to fire at passing-on forces. This is to say nothing of either side's stubbornness in defensive actions. The open terrain, generally, of the Russian steppe also led to massive battles of encirclement and annihilation, with units struggling for their literal survival, this undoubtedly added to the intensity of the fighting. Here is a single example from operations in the Ukraine, 1943:

By nightfall, the Germans decided to fight their way out of Borisovka, after realizing that the Russians had nearly completed [their] encirclement. On 7 August, elements of 19. Panzer...began a harrowing two-day fight through the Russians toward the southwest and their own lines. Blundering into one strongly defended Soviet position after another, the Germans desperately searched for a gap in the quickly closing noose.

....

There was no front and no clear idea where the Russians might be and groups of Soviet tanks and motorized infantry were liable to appear at any time and place. Russians and Germans came upon each other unexpectedly in the fluid situation. (Nipe Jr, 345-346)

Now, none of this is particularly unique, but such 'battles without front', encirclements, breakouts, etc. happened on the Eastern Front with high frequency. The nature of battle was massive, confusing, and harrowing. However, I cannot stress enough that this was only a symptom, and not the cause. That is to say, the scale and nature of combat is more a result of National Socialist effort to utterly eradicate the Soviets, that is, forcing a war of annihilation.

I cite scale, tactics and terrain as to influencing the tempo and conduct of operations, and therefore the nature of combat, but the viciousness we see is still largely a result of the total indoctrination of a German soldier. To drive home this point, I will quote several documents at length:

"THE FUHRER AS SAVIOR"

Behind the battle of annihilation of May 1940 stands in lone greatness the name of the Fuhrer....

The document goes on about Hitler's rebuilding of German dignity and state, but then begins to address National Socialism's ideological enemy...

Only the Fuhrer could carry out what had not been achieved for a thousand years....[He Has] brought together all the German stock...for the struggle for freedom and living space....When the German Eastern armies fought an unparalleled battle during the winter of 1941-42 in the snow and ice of the Russian winter, he said 'any weakling can put up with victories....'

Now, to the meat of it, exceprts from Wehrmacht handouts concerning 'Bolsheviks' and Jews:

Just as night rises up against the day, just as light and darkness are eternal enemies, so the greatest enemy of world-dominating man is man himself. The sub-man....a fearful creature, is only an attempt at a human being, with a quasi-human face, yet in mind and spirit lower than any animal.

The Wehrmacht and German regime did little to distinguish Jews from Communists...

Anyone who has ever looked at the face of a red commisar knows what the Bolsheviks are like. Here there is no need for theoretical expressions. We would insult the animals if we described the mostly Jewish men as beasts. They are the embodiment of the Satanic and insane hatred against the whole of noble humanity...the masses, whom they have sent to their deaths [in the war] by making use of all means at their disposal such as ice-cold terror and insane incitement, would have brought an end to all meaningful life....

The long story short is: While the scale and intensity of the Eastern Front is a point in and of itself, there was no 'unique' feature about it that made it barbarous. The fact remains that, as you have stated, indoctrination was the true and main cause of the viciousness of the fighting. The utter dehuminization of the enemy and setting it up as some great struggle for Europe's future - total and utter doctrinal bombardment - left little room for restraint. The Germans believed they were struggling for survival of their way of life (a farce, given that they were the invaders); and the Russians were equally indoctrinated to believe the same.