The number one reason why companies chose to migrate from Office 365 to G Suite is mobility. The future way of getting things done demands high speed and painless usage. The fewer actions you need to take to achieve the result, the better. And G Suite tends to cope with that better than Office 365.
This is why about 5 million businesses have adopted G Suite as their productivity tool in 2019. Most of them are small and medium companies who need to make their work more mobile and decentralized.