The Help for RefitTrim should state that for many/most surfaces the shape of the surface and the trimmed edge will be altered. The current help does not say anything about the surface shape being altered to some extent. This can lead the user to believe the command can rebuild the trimmed surface as an untrimmed surface with the same shape.
Also a direct statement that the shape of the trimmed edge will be altered but by adding sufficient number of knots the difference from the original shape of the trimmed edge can be reduced.