Technically, yes, anyone can be as it takes skill, time, and effort. The fact that the majority of people in this world decide not to do that because it doesn't interest them, don't want to put forth the effort, etc. doesn't change that almost everyone has the ability to do such things (within reason of course, as people with disabilities and natural handicaps due to health issues would not be able to participate). Now, if you want to talk other analogies, we could also point out that McD's cheeseburgers are exclusive to anyone without health issues, or how chocolate cake is exclusive to people without diabetes, if you really want to talk about extremes. The fact still remains that anyone's with the ability to actually play the game has the same opportunity and non-exclusive rights to step foot into a raid and get the stuff done. These items are exclusive to the people who do put in the effort.
You aren't arguing for the same opportunity for items though, you are arguing for the same items and rewards from other areas of the game, like wanting a mythic raid mount to drop from a WQ, and take everything away from people who do decide to put forth the time and effort to earn these things.