I can be quite a weight weenie, but carrying a pound and a half or so for an actual Alpine bivy can make things so easy and simple. Other areas of the country can be different but in Colorado we have so many trees that are gonna blow down and kill you in the middle of the night or aren’t suitable to tie off to for a hammock or tarp set up. And there could be an awful lot of rocky soil that’s a royal pain trying to get a stake into.
Before anybody wants to hang me for not preaching woodsman ship skills I’m not trying to say those are important but trying to get a fire going trying to maintain a fire and pitch a tarp or build some sort of a shelter can be much more difficult, time-consuming, and less reliable, along with burning more calories and risking injury or worsening an injury. Throwing on a pair of puffy pants & jacket and rolling out a bivy is almost a cheat code. For those not used to the mountain West environment, I would strongly suggest going with my preference versus the woodsmanship aspect because you can’t practice survival in Colorado living in Georgia for example. You’re just gonna go in there be naïve about making a fire and underestimating how windy it can get. Full transparency I would probably die in Georgia because I am not used to the Climate nor do I really have any practice surviving in it.