No, they are not replacing traditional keyword research. What they are replacing is a lot of the guesswork.
In my experience, keyword research tools can tell you search volume and competition, but Reddit and Quora reveal the actual questions, objections, and pain points behind those searches. In many cases, I have found content opportunities on community platforms long before they appeared in keyword tools.
The strongest strategy today is to use community discussions for audience research and keyword tools for validation. That's where I've seen the best results.