A person who does not understand mathematics might say "Math is crap." And at the end of the day, math still works, and those that accomplish great things by understanding and mathematics are rewarded, and those who don't understand or dismiss it are still subject to it.
Gene theory, genetic drift and mutations, evolution by natural selection... these theories are tools that the most successful biologists use to make better predictions and further our understanding of how life works.
Are you a biologist or a student working to enter the field? If not, then your conclusion s rather like hearing someone who's never cooked before suggest "kitchen knives are crap". Or someone who's never framed a house before conclude that "nail-guns are crap". You just have to roll your eyes. Evolution as a theory is a tool that biologists use to make better, more accurate predictions about life on this planet.
At the end of the day, we live in a world filled with an unfathomable array of diverse creatures - where those who take the time to learn and understand biology can accomplish great things and be rewarded, and those who don't understand or dismiss it are still subject to it.
- Lime