Germany doesn't get all the blame though.
Russia is a big culprit too. The reason Germany invaded Belgium/France was because it knew it was going to be fighting a two front war.
You can say "but no one had declared war on them yet" but that's a technicality. Russia had mobilized its army for full invasion, and given the timing... (with relationship to the harvest) this wasn't just for show. Russia was prepped to invade (as historical evidence now shows) and after Russia's losses against Japan/etc., it had a chip on it's shoulder and wouldn't take the Serbian thing with any sort of compromise (again, diplomatic communications prove this).
Germany could have stopped Austria, but the actions that Austria took were not too dissimilar from what was going on with other nations at the time. It was just the unlucky spark.
You can blame anyone in this conflict. Russia for escalating things in an attempt to remain relevant (even though they were not prepared and lost the war so hard that Communism took over). Germany for being too aggressive with their political ambitions. France and the UK for joining a military alliance that would automatically put Germany in a two front war (with legally binding clauses that to other countries would look like guarantees that any war among one of them would involve all of them). With that last one... seriously, it meant that any conflict among Europeans was on paper meant to be a world conflict.
Germany was the bad guy in WWII, but the only truly villainous force in WWI were the rising tide of unchecked nationalism, complex defense treaties, and lack of foresight.