iComparible vs iComparer vs Linq

Hi there, I was pretty much a blank slate to the iComparer used in the video. After Checking out documentation and youtube videos for an hour I came to two hypothesis.

1) I tried to do this with the iComparable method first, and it was impossible because the PointsPerGame is a floating point variable. Can we get the same result with iComparable?

2) iComparer(and iComparable) are obsolete because we can call linq expressions on Lists (this is possible becuase List<t> implements the iEnumerable class).
Do I have that right?

Here is the solution (that I got from notes I took on an earlier Carling course)

public static List<Player> GetTopTenPlayers(List<Player> players)
       {
            var _Players = players.OrderByDescending(a => a.PointsPerGame).Take(10).ToList();
            return _Players;
        }