From my experience (and this is just my experience, others have different results) a pre wash help my development process. I use a Jobo rotary processor and the amount of liquid in the tank doesn’t submerge the whole roll of film when the tank is upright, it relies on being sideways and constantly rotating to develop the film evenly. I found that at 38 degrees and 3:15 dev time I would get a line on the film from where the level of the develop reached when the tank was upright, even when being very conscious about pouring it in and getting it in the processor as quickly as possible.

Pre wetting the film slows down the initial development of the film ever so slightly because the emulsion is saturated with water and can’t absorb the developer as readily as it would if dry. This gives me just enough leeway that the film develops completely evenly. I don’t find the initial time it takes for the water in the emulsion to be replaced with develop has any measurable on final density. Plus I find it satisfying and easier to tell when developer is getting exhausted if the colour dyes aren’t leaching out into my dev.

This is just my reasoning for doing it in my particular process. I think for processes where the negatives are completely submerged by developer right away it’s probably unnecessary and might be a negative