It's a complicated issue. The content is not brutally hard, unforgiving, etc. If I had any 6 of the whiners accounts, I could clear 6/6 delve in a day without any outside help(maybe +1 day on job leveling if their combination was particularly bad). If you got a group together and tried for a while, you'd win. This is what people had to do when delve1 came out, remember how it took over a month before anyone had even cleared a T6? That wasn't for lack of trying, dedicated groups were bringing full coordinated alliances and getting their asses kicked while they worked out the strategy and farmed up the gear needed to do it. Now, the strategies are known and you can go right ahead and pick up gear good enough to win for the sparks you got for free while leveling to 99.

The attitude spreads itself, though. If you shout as a BST, a sparks-DD, or even someone known to be new-ish.. nobody will be interested. The other new people may see it as futile, or see themselves as unworthy. There isn't a quick fix to this, and it may not be solely the fault of the players. That doesn't mean you should let it keep you down. If you want to advance, you have to put the time into making a group and (this is the important part) stick with it. The only surefire way not to win delve is not to try delve.