It's very important to stay on the trails and to pay attention to the routes on these hikes. They are there for a reason because a lot of times the areas surrounding the trails isn't safe. In many instances where hikers disappear it's because they decided to go off the designated path and either got lost or had an accident.
We have no information that FB planned to leave the trail. In my opinion, judging from her profile, it seems very unlikely she would have done so. She was not in the "high testosterone" demographic, nor a trail runner, nor someone who inappropriately applied past experience to an entirely new situation (e.g. assuming skills developed on the Long Trail in VT during summer would be the same as needed in the WA Olympics in any season). The last 3 examples are where we've seen the majority of long-term missing backcountry accidents lately, I believe.
The Prairie Creek area in the Sawtooths is a notorious area for losing the trail if you try to do a loop. If you went to filter a new batch of water, you might fall in. You might simply step off a cliff. So, yeah, let's not lay this one on FB as a high-risk, "she tempted fate, and fate happened" kind of thing.
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I'm not sure what pack FB was carrying, but here's the deal. I am flabbergasted by how many people I see out there with small packs. Ridiculously small packs and trail running vests. Some of the most popular hiking packs (e.g. the Osprey Talon and Tempest <30 liters*) are too small for the 10 Essentials. Even a mini-size ditty bag of essentials plus a jacket of some kind plus enough water won't fit in a daypack/vest like that; and for a riskier context, certainly a full-on set of essentials won't fit. And depending on other hikers to supply you with essentials if something happens to you (e.g. when raining, ultralight backpackers have been known to pressure others out of sleeping spots at shelters because their weight fanaticism persuaded them not to carry a tent) is just not right.
FB went missing before iphone 14 (with satellite SOS), but now this is all it takes on low risk hikes to have some sort of communication and access to help. Not perfect, but a great risk-hedge, and you don't have an extra service subscription cost, just your regular cell plan. An iphone 14 would likely have been effective in the area where FB went missing because there are open areas. If I did a lot of wilderness activity, I'd want something I could really count on: e.g. an inReach.
Finally, if you ever have expiring coupons at an outdoor store, and you don't know what to get, buy paper maps for your hikes. They could save your life next time you head outdoors on an adventure, or alternatively, let you plan the trip of a lifetime.
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My recommendation always is to learn backcountry skills by heading out with a long-established hiking club (not and SM-organized ad hoc kind of thing). Listen to "old-timers": most backcountry risk-lowering skills have been in place for decades, and old-timers know what works and what doesn't. They will look at risks in a way that you and your social group can't imagine. This is helpful! There's Outdoor Afro, the Sierra Club, Obsidians, Mountaineers, AMC, Green Mountain Club, Latino Outdoors, many, many many.
IIRC FB learned her skills in a context of club-hiking. This is why I have faith that she wasn't doing anything extremely risky like deliberately bushwhacking while solo, and simply met with an accident.
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*<30 liters daypacks made by other companies may be large enough, so I'm not tarring every pack with the same feather! It depends on the pack, the company, and how many games they're playing with ounce-counting so as to appeal to purchasers.
