I think you are a bit over the top here. Hindsight is always 20/20, and there certainly are a few things that they could have done better, but overall they were reasonably prepared for that journey. Let's consider a few of your comments:
The arctic is these folks' home, winter and summer. They know what they are doing. They survived 8 days with no harm. I suspect some of the commenters here on ETS would have a hard time surviving 8 hours in the arctic in winter

They had one sleeping bag and mattress. An igloo is vastly superior shelter to any tent in those conditions. They obviously had good arctic clothing (riding a snow machine in -30C you would freeze in moments without it). They had a stove and fuel, which lasted 8 days.

They had tea and sugar. They shot a caribou, so they had plenty of food. Presumably they had a rifle to shoot the 'bou. They had enough stove fuel to last 8 days. They stayed hydrated (a big deal in the arctic).

This may or may not have helped, depending on how far off route they were. Gas is heavy. The more spare gas you carry, the more gas you burn. Depending on the terrain, carrying too much extra weight can lead to other problems.

This is probably the one thing you list that would have made a big difference.

Bottom line is I think they were reasonably well prepared, and did quite well under the circumstances. Surviving 8 days in arctic winter conditions with no ill effects is no small accomplishment. True survival incidents are always graded "pass/fail". They clearly got a passing grade.