Not saying either side is right, but I was playing Warthunder earlier, which is basically a lobby/matchmaking based FPS (with tanks and aircraft instead of infantry). It is very intense, action based, and I spent about 4 hours playing with absolutely no lag. And it's not even installed on my SSD, it's on my Programs drive, which is mostly for old DOS games right now (too lazy to install much at the moment).
While DDO is far from simple, it also isn't as heavy on collision detection and such as a FPS. And it's almost returning to it's turn-based roots in some instances nowadays.
The thing is, I'm not certain it's even anything to do with the networking. I froze out earlier tonight in The Necropolis. No one there, nothing going on, but I was locked down, and just barely managed to turn around and return to House P. The rest of my party, who took the ship to the Orchard entrance, were lagging. In house P, both before and after that lag-filled mess, I was fine. No latency or loss according to DDO's own network icon. Other times I've lagged, it only happened when special mobs (such as orange/red named bosses) appeared, and the lag was gone when they were dead. But only on certain runs of the quests. I can reenter immediately after, and not get a bit of lag the second time through.