Back in the 70's, I was very fortunate to make friends with a veteran photographer. Shortly before I shot my first wedding, he invited me to his home, sat me down at the kitchen table, and reviewed everything I needed to do as a wedding photographer. The first thing he told me was, "You need a bigger camera." Of course, many advances in film photographer have occurred since then.
In those days, retouching was done directly on the negative. 35mm is just too small to do this efficiently. The guideline used to be a head size (on the neg) at least the size of a dime. Of course, the lager the neg, the better the work possible.
Printing just 8x10 showed a vast improvement over 35mm. Anything larger just didn't look professional.
Cropping an image was pretty much out of the question too... unless you were making custom prints. Using negative masks for a multi-printer allows more choice for roll film users without the added expense.
There was a time when film choice came into play too. Some pro films were not available on 35mm. Sometimes it went the other way. When Kodak introduced their 110 cameras along with a "new" fine grain film, they limited production to armature sizes only.
In my situation, I have to shoot digital now. I went kicking and screaming with my heels dug in. I waited as long as I could... maybe a year or two too late. It wouldn't be practical for me to shoot film now... with the added cost and increased delivery time.
But, back to your question... to get results that were up to par with other studios, it was necessary to use roll film. 35mm was reserved for making slides and photojournalism.
I still believe roll film is necessary to make quality wall prints.
Pete