Getting into a sleeping bag and tent only works if you have insulation sufficient for the temperature and all of your insulation is dry. A fire is typically made when that is not the case. A fire gives you external heat. You can survive almost any low temperature - just add more wood. Ray Mears claimed that with a lean to, raised bed, and a long log fire, you can survive down to -50 degrees without a sleeping bag. He has the experience to back that up.
If you are day hiking and get stuck overnight, a fire is the only way to stay warm unless you are going to crawl in a emergency bivy and tolerate being borderline hypothermic.
This does not work when you are exposed to a storm. You need to be in a sheltered in a forest, don't even bother trying to make a fire in a storm on the side of a mountain at the timberline.
A tent and fire are not compatible. A tarp and fire pair up nicely. Set it up lean-to style, as a canopy, or as a 3 sided shelter with a small opening and you can heat yourself with a fire placed a safe distance in front of your shelter. The tarp reflects the heat to keep your back warm. This is standard procedure for my winter trips when setting up camp for the night. We have a shelter place to relax under while being warmed by a fire. It really saves weight over carrying super warm camp clothing. If I expect it to get extra chilly that night, I will drag over a few more logs and if I wake up cold in the late hours of the night, I can warm right back up. I rarely hike in an area where a tent is necessary and the weather is harsh enough to make a fire impossible.
Being in the pacific northwest, I understand why you are skeptical of fire as a survival skill. All of that moisture can make a fire extremely difficult.