In the summer of 2002, dozens of us HPA members went on a habitat tour on the SF that adjoins the Grand Canyon (up the West Rim Trail). Pretty much an all day event and very educational.
The first area we spent time at, was a fenced exclosure that had very good regen inside the fenced area. Most of it had been close to a clear cut several years previously (several mature trees had been left in place to foster desirable regen, so it wasn't a total clear cut). Parts of it resemebled a jungle, as the growth was very dense in some areas, depending on what was prospering there.
Outside the fence, clear evidence of severe browsing on the same vintage cut that wasn't fenced. Every oak stump was devoid of sprouts, any other regen was also browsed into oblivion. So there were enough deer there to show the difference in what occured inside the fence and what went on, outside.
My favorite comments on such exclosures, are the ones saying "Sure the outside was browsed-off, the deer couldn't get to the inside".
Yet some still deny the adverse effects deer can have on forest regen, ridicule deer exclosures and the reasons they exist in some areas.
The next stop on the tour, was an area farther north that had once been fenced, but no longer was. Desirable species had been able to mature enough, that deer cold no longer affect them, then the fence was removed. Good mast production and many other benefits from regen that was allowed to grow, rather than be eaten into oblivion.
Many of us figured out the "why" parts of such measures long ago and why it also became necessary to bring down deer numbers at the turn of the decade in many areas of PA.
Others? Not so much. But I reckon if your personal bottom line is limited to always seeing "enough" deer each fall, then ya probably don't spend much time worrying about anything else other than that? No worries about a sustainable habitat to ensure good wildlife numbers for years to come, just "gimme what I want right now".