It seem to me, that the issue at DCC is potentially one of format. Expecting these players to play for X number of hours in a row, can't be an enjoyable experience for them, or the fans. In the "old" days, SOME of these folks/players would be jacked up on amphetamines, cocaine, booze, or a combination of God knows what, in order to achieve seemingly inhuman feats of longevity at the table. In the long run, that isn't good for anyone.
Think about the reasons for any sports popularity, or lack thereof these days. It generally revolves around attention span. Golf, baseball etc, all suffer to some degree from the curse of "who the hell has all day for this crap?" Even local poolroom tournaments suffer participation issues from "older" players, because they just don't want to be out until 2 a.m., in order to compete, should they be fortunate enough to advance deep into the tourney. I'm probably combining a few different threads worth of rant here, so I offer my apologies.
In the case of Frost, Shaw, etc, it's hard to say. It could have been exhaustion, illness, etc...Sometimes you just realize that it isn't your day, and that you're being thoroughly beaten. That being said, I'm not suggesting that anyone concede, I'm just offering opinions. It's a tough call. Perhaps Shaw/Frost just felt themselves coming unglued, and decided that a gentlemanly concession was better than an epic, anger filled meltdown. Who truly knows what someone else is feeling at the time that they choose their path?