Well you can’t just throw a Molotov because in that case you’re going to get caught. You can place a drone, go home and have it drop the Molotov the next day and no one would know who did it.
Drones aren’t as anonymous. Not sure about other brands, but DJI requires tying it to an email and phone number. It also sends back home a lot of information about your phone, geolocation, network, etc. I’d be surprised if they couldn’t easily tie it to your real life identity.
A few folks on this site might know how to work around these measures. Most of us would probably fail on some subtle way. You’re average terrorist isn’t nearly as tech savvy.