There are two significant reasons for building your own web Infrastructure, rather than using online services.

Security / Privacy

If you use an online service that is 'free' and you aren't paying for the service, then YOU ARE the service. It costs money to put things in 'the cloud'. These services must rent hosting server computers somewhere. If they aren't charging you for that, then they are making money off you some way. That could be by displaying ads, or it could be by sharing information about you or your file contents with others in exchange for payment for that information.

You may think that you aren't storing anything of value. However, if you upload a spreadsheet or other document that lists all the members/attenders of your church with their contact info (i.e. a 'church directory'), that information is very valuable to others - both the general data but also the indirect data that indicates that they are regularly part of your church.

By hosting your own systems you maintain the responsibility of who has access to your data. You do have to take the responsibility to learn how to keep that data secure, but you are a much smaller target for hacking as a small individual server than if your data was on a system with hundreds or thousands of other organizations data.

Availability

If you use any online service provider you are at their mercy. They may decide, with little notice, that they are going to discontinue the service. This happens not only with smaller companies but big ones also. The list of services that Google had made available free only to later shutter is growing every year.

By hosting your own services (on a server you lease or a server physically located within your building*), you can ensure that the services are available when you need them. You can decide when updates take place that may affect your access to the services.

*NOTE: We do NOT recommend hosting file or document-sharing services on your own physical servers at your own location. This is partly due to the advanced knowledge required to keep the servers running (which if you have that knowledge, you probably would not be reading this), but primarily due to the fact that most ISPs (Internet Service Providers - Comcast, Century Link,, AT&T, etc.) may limit the number of connections to your location.