People dash off because they can. If a party has even one competent healer and tank, they can pretty much duo the fight, throw in a couple of Novus geared DPS and the fights are an absolute cake walk. People are so grossly overgeared that not getting healed for a while at start isn't a big deal. The beginnings of encounters are not dangerous anyway. The locked CS circle pretty much makes the transition screen the only possible load time when the party can dash off, and that barely lasts a few seconds with a normal connection. We're literally talking about a time period of seconds here.

And since when was wiping to content the only way to learn it? If you can win with less people, you might as well win the fights while you learn.

It's old content, people are gonna rush/farm it. New people are going to have a different experience with the fights than the people who played a year ago. Those are the realities and people need to accept that.