Very heavy tent JUST SIMPLY COLLAPSED. That's it, no other mysteries. There were NO AVALANCE. The bamboo ski poles that were suppose to keep very, VERY heavy tent up and liveable, gave in, making the tent collapse on top of them, in hevy snow fall, blissard, icy snow piling on top of the tent, and making the tent even more heavier. Strong blizzard that made the tent shake or move a bit loosened the ropes. The ropes that were tied to the sticks and skies gave in, or they were loosely tied, or the sticks just gave in. Or the ropes were weak and broke.
This is very simple explanation.
The tent itself was made of two tents that were put togeher, and this needed some extra support to keep the middle of the roof up. I have seen in other pictures them using ropes tied to trees to lift the roof top up from the middle. Now they didn't have that opportunity, or trees to tie the corners of the tent to keep it from collapsing, so they used skies and I suppose ski poles. it wasn't good enough.
After the tent collapsed, the group inside felt all the air escaped from inside, and maybe together with snow on top of the tent roof felt they were choking in lack of air. They perhaps tried first to open the door, untying the knots. I had this kind of tent long ago at 70's. But because the tent was down and had collapsed, finding the doorway, opening the knots one by one became difficult, and too slow in pitch darkness, maybe even impossible. Aren't the knots outside of the tnet, making it difficult to open from inside? I believe 2 knots had been opened from the bottom, unless I am wrong. The people inside started to pass away due lack of air. Or even if there were enough air, they or one of them panicked anyways. They maybe thought the door is too slow and difficult to open and they or just one of them became too hasty and cut the tent to get air.
I have seen one picture that somebody drow about the collapsed tent. You see it if you google "Dyatlov tent" from Google picture search. It shows the other side of the tent was collapsed, and there was one broken ski pole, but that was cut intentionally(what ever that means)...
So somebody or more of them cut the tent and they all came out from tent. This led to another situations that we all know. The tent was badly ripped open, it was no use anymore, or at least not much. Maybe some paradoxical undressing already happened at this point, who knows, and that's why they didn't think they needed the boots and all clothes. But they became in a hurry to get a fire, maybe a fire to the stove. And for that they needed wood. They didn't have any wood with them, because they hadn't planned to use the stove that night, The "grade 3" certification that they wanted demanded them to sleep in cold some nights without stove ( correct if I'm wrong). So they weren't planning or prepared to use the stove that night, otherwise they would have put the tent near the forest to get wood. So they had to leave the tent, maybe not permanently but to get wood for the stove, or to find a snow cave, to get away from horrible blizzard and windy mountain.
And then part of them died in hypothermia, part fell to that deep hole and were crushed, and part tried to get back to the tent (maybe carrying some wood or not), or tried to get more clothes from tent, but weren't able anymore.
I might add one other thing. It is very poosible also that there were fist fight between the group later once they were in the forest. Maybe some got very angry to Dyatlov or those who cut the tent, or those who's resposibility it was to put the tent up properly...this is because there were bruises on their faces and fists...But who knows....