Oxygen bars aid in recovery, they don't speed up acclimatization, but they do help you recover after a long day of exercise at high elevation and give you more energy. Just as a fire can’t burn without oxygen our cells can’t produce heat and energy without oxygen.
When acclimatizing, climbers spend the day climbing high, but then sleep at lower elevations to regain their strength.
On Everest for example, this is a typical schedule for acclimatizing:
Trek to Base Camp (BC) from Katmandu - 10 days
Arrival BC April 1
Climbing Camp 1 (C1) April 7
Back to BC April 8
Climbing C2 April 11
Back to BC April 13
Climbing C2 April 17
Climbing C3 April 19
Back to BC April 20
Trekking down to Katmandu April 21
Back to BC April 26
1st summit attempt May 1-7
Trekking down May 7-12
Back in BC May 13
Last summit attempts May 16-30
You'll notice that they don't just progress slowly from camp to camp up to the top, and they don't spend a lot of time up high, they take their time over a period of almost 2 months climbing higher and higher, but always retreating to lower elevations to recover. Before they make their summit attempt they actually leave the mountain and spend about a week at really low elevation regaining strength.
Your level of health does not decrease your body's dependancy on oxygen,
oxygen always has something to offer your body, it's necessary for every body function and is literally the most important substance your body consumes. If you think hydration is important, Oxygen is infinitely more valuable, just as your body will operate better while super hydrated, you'll perform infinitely better if your cells have more oxygen.
The bottles will benefit an healthy person just as much as they will an unhealthy person, they give you more energy. Call it a fleeting boost if you will, but it's better than any boost energy drinks or electrolyte gels can offer. All the snacks and drinks you bring for energy on a hike aren't any good for you anyways unless you have a healthy amount of oxygen in your blood to extract the energy from them, this is exactly why people at high elevation experience a lack of appetite. More Oxygen = Better, always.