Journaling absolutely works for many people, but it isn't for everyone. Whatever helps you examine your inner self - as well as gain a better understanding of where you've been, where you're at currently, and where you want to go - will work. Give it a try, but don't pressure yourself to make it work simply because it can be successful for others. There are many paths leading toward mind-body healing.
My journals have always consisted of short recollections of specific memories (e.g., funny stories from a crazy Friday night - certainly not mind-body related). While in the process of healing from my worst symptoms, I responded better to talk therapy as well as cognitive behavioral therapy. Talking out loud was very helpful in my case. At the same time, I also benefitted tremendously from posting on this forum, which is certainly an important form of writing - even if not in a personal journal.
There are many options, hence the differing expert opinions. What does this mean for you? That you can rest assured that there is a path for you in mind-body healing, whether it includes journaling or not.