Ken, what part of the Wilderness Act are you reading that brings you to
conclude that those people "have not experienced Wilderness"?
"an area where the earth and its community of life are untrammeled by man"
Just addressing the first part...
Definition of "untrammeled": not limited or controlled; unrestrained.
I do not understand how unreasonably tight quotas limiting access to wilderness on a trail advances or enhances an area's being "untrammeled by man". Hikers visiting the wilderness are not limiting, controlling, or restraining the landscape, environment, or the habitat. Using that phrase to support keeping people out is ridiculous.
As for "What is a Wilderness Experience", whether a lone hiker visits such an area, or 50 do on the same day, the fact that the only man made effect they see is the trail, then I would say they had a Wilderness Experience. The number of people they met on the trail has nothing to do with that.
It seems more that the phrase is in the Wilderness Act definition to support the idea that no man made improvements or changes be allowed. Of course trails and trail building has some impact, but at least we agree that trails are ok.
