Whenever someone ditches the group right at the final boss, it can sometimes be far too difficult to find a replacement or continue without them, forcing you to abandon it. I mean, the option to throw yourself into a no-win scenario over and over again for an hour is still there, but there is literally zero fun in this.
Why can't we save our progress so that we can continue another time?
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And the first person to say "It'll be exploited" can just leave. I KNOW it can be exploited, but that's not good enough of a reason to deliberately leave out a feature like this. There are far too many things in this game that punish people who are just victims of circumstance, and they intentionally aren't fixed because of the fear of people exploiting them for their own benefit.
Guildmaster of Spectral Liberty - Xbox One - European Megaserver