Yes and no. To take your anarchists with bombs - sure, the specific moment and way to start WW1 depended on that. But at the same time, the network of defense

Yes and no. To take your anarchists with bombs - sure, the specific moment and way to start WW1 depended on that. But at the same time, the network of defense agreements led to a rise of regional power blocs (increasing polarization). The Anglo-German arms race led to a surplus of military, and an increasing rift between the German and the British bloc. The Russo-Japanese war caused a shift of Russian interests to the Balkans, which also mattered to Austria (sort-of part of the German bloc). The insults of 1870 and the Marocco crisis led to a deepening rift between Germany and France. The Italo-Libyan war exposed that the Ottoman empire was extremely shaky, further stoking interests in colonial expansion. Which promptly happened with the Balkan Wars. Those anarchists with bombs were the particular match to a powder keg sitting around. Chances are there would've been a different match on a different day, had this not happened. Maybe there still would've been a small path away from the conflagration if the assasination and consequences hadn't happened. But each previous event narrowed that path. History may be path-dependent, but there are some paths that are narrowing down the options you can consequently take. The same holds for Rome - the actions taken increasingly narrowed down the possible ways forward. (And that, I'd argue, are the main lessons to draw from any collapse - what actions narrowed the solution space, which ones broadened it)