For button spamming, there are third party solutions like "turbo" key and even gamepads with "turbo" mode for buttons (does the fast mashing for you).

As for story raids, i never seen anyone willing to insult anyone for being down, or dead and finishing the fights, it just happens in story mode, maybe getting a Free company that can understand that and help you go through these phases / fights in the story. You might even find people that would happily help.

The Nier raids and a lot of alliance raids are often optional and not part of the main story.