To argue against this statement, we should focus on the terms of the treaty that were arguably excessive.
First, we should look at the fact that the treaty blamed Germany for the war. This was unfair given that Germany was not the only country to blame for the outbreak of WWI.
Second, we should look at how harshly Germany was treated because of this assumption. We should look at the amount of reparations they had to pay. We should look at the fact that they had to give all of the production of their coal mines in the Saar area to France. We should look at the fact that much of their territory both in Europe and overseas was taken away.
All of this was excessively punitive given that Germany was not solely at fault for the war. It is not unreasonable for a country to react with great anger to harsh conditions imposed unfairly.