The argument of the alphabet soup lobby is that conversion therapy is inherently ineffective and harmful. That's not how therapies work. Even if certain methods of therapy may fit that mold, that does not mean that all such therapies that now exist or are ever to exist would be inherently bad and worth banning. The Colorado ban and others like it, pushed heavily by the lobbyists, are the only therapies I know banned based on intended outcome, rather than method. They want to literally make it illegal to even try to achieve heterosexuality.
It is in a person's best interest not to engage in sodomy. One cannot reproduce that way and it is a harbinger of all sorts of infectious diseases. A successful conversion therapy that steers a person away from sodomy is a net benefit to that person's life. The lobbyists want to categorically forbid it.
It is in a person's best interest to be in harmony with one's own biological sex. Current methods of attempting to change one's semblance to the other sex are incomplete, can cause permanent damage, and yet it is the alternative—therapies that target the neuroplastic mind to address the root dysphoria—that the lobby wants to ban.