Well Moscow was the railway hub for the entire Northern section of USSR. Capturing Moscow would most likely cut off at minimum 70-80% of all supplies flowing to the finish border and Leningrad. Considering how much this extended the front for the Axis and how many troops would be freed up from this, it would actually mean quite a lot.
What would a few hundred thousand troops in Finland and surrounding Leningrad be able to do for the Axis?
If Germany had taken Moscow in the fall, Moscow would have almost certainly been an even larger disaster for Germany than Stalingrad was a year later. Germany was at the end of its rope in 1940, by that I mean it had out run its supply and logistical support. The soldiers were simply not prepared, mentally, physically or in terms of equipment to hold onto Moscow. Had Germany taken Moscow, the Soviet winter counter offensive still happens and Germany occupying Moscow was NOT going to fall back. Hitler would have ordered his armies to hold fast. Goering would have said he could air lift them, and you'd have almost certainly seen a total collapse of AGS.
As it was, since Germany had not yet actually taken Moscow, they were able to fall back in the face of the counter offensive and eventually blunt it.
Another poster made the comment about delaying the offensive to deal with Soviet armies in Ukraine. That was the correct decision. People don't really understand what was happening during the summer and fall. Surging headlong for Moscow ignoring a massive Soviet force on your southern flank would have been the ultimate in stupidity.
By the time Germany had reached Moscow, it was a spent force. It had taken casualties in the 6 months that it simply could not replace. The primary group structure that the Wehrmacht was built on, was
GONE. The Primary groups died in the USSR and the Wehrmacht was never the same after that.
The reason? Yes, while Germany inflicted ~5 million irrecoverable (KIA, WIA, POW) losses on the USSR in that opening 6 months, the Red Army was launching brutal, suicidal, and ultimately effective counter offensives whenever they possibly could. These counter offensives have been largely glossed over, ignored, or they have been erased from the historical record as best as possible. The USSR tried to downplay or make go away these operations because they ultimately were embarrassing if you look at them in a zero sum light. They all failed in that respect, but they also succeeded in pulling Germany into a brutally costly slog. Germany paid dearly for its advance.
This is why leaving armies on an unprotected flank in the Ukraine was simply a non-starter. If you drive past them and leave them, they WERE going to attack, and they WOULD have caused massive problems.
As it turned out, Germany didn't take Moscow in the fall, and when the Soviets counter attacked in December they were not invested in Moscow. Taking Moscow for Germany would have been quite brief. At the end of 1940 Germany simply was not in the position to resist the Soviet counter offensive that came, and had they taken Moscow, ignored the armies in Ukraine, and stretched their supply lines and logistical capabilities even further. Well, the collapse of AGS is almost academic in that case.
Here is what happens if the armies in Ukraine are ignored. They begin launching attacks sometime in October or November. Since there are no strong military forces of sufficient strength in the area to actually blunt the offensives, you end up with even more logistical problems as they undoubtedly make some inroads, cutting some supply routes, and otherwise cause a big problem. At this point strength will HAVE to be stripped from the Moscow area to deal with these offensives in Ukraine. Those forces cannot come from anywhere else.
Then in December when the Soviet counter offensive hits, regardless of them holding Moscow or not it was coming, Germany is not outside of Moscow, the armies are IN Moscow. Germany was unable to resist the offensive historically, and it was allowed to fall back with the blow. In this situation there is absolutely no way Hitler is going to authorize a retreat from Moscow. The armies are going to turtle up, get encircled and now what?
How is AGS going to be rescued from Moscow in December and January? Logistically it is going to be weaker than it was historically. The casualties would have been enormous.
