I know a lot of people place the blame for lag on connection. However, this is still SE's fault, because they didn't compensate for it.

These are Japanese developers. They don't make a lot of online games like our western developers do. They also enjoy a far more powerful internet service in their country. Fiber right up to everyone's house as I understand it. Western game makers put a lot of effort into minimizing or compensating for the delay in our long distance copper heavy network.

Normally this might not be an issue, but SE also designed a lot of the end-game bosses with very lag sensitive mechanics. Titan HM and EX are the prime examples of this.

These two points are why SE is at fault here. They need to recognize the kind of network we are forced to play on. They need to provide better netcode that can compensate for lag problems, like making character positioning client authoritative. They also need to take lag into consideration when they design a boss fight. For our EU friends, they also could have provided localized servers.

You can blame ISPs and routes all you want, but it's still SE's responsibility to provide a playable game, especially when we are paying a service fee.