I used to be a mental health professional for just over 3 decades before I had to stop working due to ill-health but, I totally understand and agree with what you’re saying. We would encourage our patients to take up journaling as a way to provide therapeutic support for them, and every patient we discovered would be shattered the next day.
Emotive writing does hold a very powerful for the writer despite the emotional drain it can cause short term. The trick is to have the next couple of days doing some good self care.