With very few exceptions, people have downtime between training. That's a perfect time to have this discussion. I myself do a lot of posts while I'm working at my day job, waiting for loading bars to crawl across the screen or spinny circles on an application to stop spinning so I can use it again. During this time I can't exactly spar or hit the heavy bag, but I can discuss martial arts. By your logic, anyone who has time to post on here isn't serious about their training. Because every post here could be time spent training.
Also, even when you are training, you have to evaluate your technique. Nobody's going to learn to punch by just punching over and over again. Otherwise martial arts schools could be replaced by a pamphlet that says:
- Do 1000 punches
- Do 1000 kicks
- Do 1000 elbows
- Do 1000 knees
- Go shower
There's a combination of technical discussion and training that goes into making someone a good fighter. Just because you train, doesn't mean you don't have time for that discussion.