"There are other ways to evaluate potential candidates.", but I have some reservations about many of your suggestions.
"Most people have a LinkedIn profile these days which usually duplicates the majority of things on a CV."
There are three problems with this. One is that not everybody should need a Linkedin profile to apply to a job. Most of them will have it, but not everyone. The second is that a CV can be tailored to the job, listing qualifications of interest to them without listing the things they won't care about. True, it can also have lies on it, but so can a profile. Third, even if we assume the two contain the same content, you could either write a bot to scrape the data from their profile and analyze it for you or have the candidates send you the information in a more readable format that requires no coding or searching to quickly scan. The resume is the easier method for both sides.
"GitHub repositories of personal projects and StackOverflow comments/answers/etc can give an indication of practical knowledge."
Yeah, I generally don't like this. I don't post answers on Stackoverflow often, and when I do, I don't post under my name. I don't think answering people who potentially don't have a clue what they're doing shows much about my practical knowledge. It would speak better of my ability as a teacher, but even there it's not great.
Github is a little better, but it also can be risky. My Github projects are those things that I do as a hobby, at least mostly. That means they're not necessarily the stuff I have the most experience with. If my job is mostly writing a process that runs on servers, but in my spare time, I'm writing something that runs on an embedded system with limited resources, someone reading my Github will get a skewed image of what I know for two reasons. They could misinterpret what the project is and assume that the hacks I'm using to fit my program into the limited resources are what I would do all the time. Even if they don't, they could assume that I only know embedded stuff, and take my less experienced code as what I can do there. This would not take into account that what I write at work can be different and better. Yes, I have multiple repos out there, but not all of them are updated and some of them are simple tools that are useful to me and others but not particularly complex.
The coding challenges before an interview can be a better filtering system as long as they're realistic.