A few days ago Microsoft announced that you will be able to use an Azure Storage Account as SFTP (Secure File Transfer Protocol). This is a feature that a lot of people have been waiting for a long time. Please bear in mind that SFTP on a Storage Account is still in preview and lot might change in the regards to functionalities.
Azure SFTP is the right now the closest thing that you can get to FTP-as-a-Service, it’s something that I have been looking forward to myself for a long time (I can now finally shutdown my FTP server maybe). The need for (S)FTP has been in decline for a long time because there are a lot of great tools out there that can be used to share files and collaborate on said files. (Microsoft SharePoint, OneDrive etc.)
The need for SFTP is from my point of view still valid, when you need to share a large file with another company. One case for it is that you need to share a big database (.bak) with another person. Another case is you need to receive a lot of files from a vendor that you need in a program. Then SFTP might be more suited for your needs.
As I said, there are still many valid needs for SFTP.