That argument has been made at various times. It is not completely outlandish. It was not a matter of dominating Europe nor America; those efforts came about from the relentless escalation of the war as a result of the rats nest of interlocking treaties that were in place at the time. It’s hard to argue that a German crackdown on Serbia as a result of the assassination, even if it might have been brutal, would have been more distasteful than the whole of WWI and the eventual outbreak of WW2.
Germany wasn’t involved in “cracking down” on Serbia; they supported Austria-Hungary against Russian interference so THEY could.