As for technical attacks, I'm not an expert but I'd assume it's more difficult for bad actors to bring down decentralized networks. Has the BitTorrent network ever gone offline because it was hacked for example? That seems like it would be extremely hard to do, not even the movie industry managed to take them down.
Depending on scale that’s not necessarily true. I find even today there are many services that cannot keep up with my residential fiber connection (3Gbps symmetrical), whereas torrents frequently can. IA in particular is notoriously slow when downloading from their servers, and even taking into account DHT time torrents can be much faster.
Now if all of their PBs of data were cached in a CDN, yeah that’s probably faster than any decentralized solution. But that will take a heck of a lot more money to maintain than I think is possible for IA.