Dating norms exist. They vary from culture to culture and over time. The natures of norms and humans are such that there will be large scale average behaviors and some varying proportion of the population will consist of outliers. Toxically optimistic platitudinous advice such as this only ensures a perpetual class of lonely, dissatisfied people, primarily men.
Historically the rate of reproduction among men has varied, anywhere from 4/5 to 1/17. Lonely men need to be proactive and most importantly realistic, and understanding current preference norms and in what ways these men fall into or outside of them is critical to evaluating which aspects of themselves they may improve, and to what degree their immutable characteristics realistically limit their chances of attracting mates that they desire.
Hypergamous cultural norms, like those toward which the west is moving, create masses of perpetually frustrated men, many of whom who at best lose interest in participating in society, and at worst become bitter and violently antisocial. Thus movements which tilt dating norms toward hypergamy create unstable and dysfunctional societies. I know that your advice is given in good faith, but your relative is not the toxic one.