why does mongoDB provides two more update methods {db.collection.updateOne() and db.collection.updateMany()} when we already have db.collection.update(,,{multi : true/false}) with value of multi as true or false ?
We introduced db.collection.update(,,{multi : true/false}) before updateMany when we only had update method but based on user experience or product, we have introduced updateMany.
If you have any issues/suggestions/feedback, do let us know. 
Kanika