The first alpine style ascent of that peak without oxygen was done in 1978
No. The 1978 ascent was not alpine style. You must be confusing the 1978 expedition with Messner's solo ascent of the Tibet side in 1980.
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Personally, I don't care how anyone climbs Everest as long as they leave the mountain clean and don't put other's lives in unwarranted danger. When it comes to climbing ethics, leaving the mountain clean is the #1 priority and in modern days should always be so.
As long as you pack out your bottles, I see nothing wrong with doing it since it is a personal choice and nobody's business (unless you are lying about your ascent or lying about using it). I also find it ironic that some (speaking generally to all climbers) that complain about using supplemental O2 on climbs are the same people that are using bolts on rock routes, which is more cheating than using supplemental O2. I have also cheated many climbs by using bolts as well, but it is still ironic that those that do complain about others using O2.
When it comes to Everest, Ed Viesturs puts it best (Sierra Magazine interview):
Everest has been so frequently climbed, commercialized, and, some would even say, turned into a circus. Is Everest worth it anymore for a serious climber?
Thankfully, I was able to go in the late 1980s and early '90s, when the mountain was very quiet, relative to what it is today. But as a serious mountaineer today, you've got to realize that there's just going to be a lot of people there. There's no way to say, "I get to be here, and these people shouldn't be here." That's not fair either. You can go to other sides of the mountain. You can find quieter corners of Everest. And if you don't want to go to Everest, then, well, go somewhere else. I would also add that you can climb it in another season. Almost all ascents now days are pre-Monsoon. A very few are post Monsoon, but these are rare now days. If you don't go in April-May, chances are that you will have the mountain all to yourself, even on the standard routes.