What is the advantages of storing data in external – online databases?

You saving your time.
It’s all working – you don’t need to download/install/configure/learn databases.

You just get it all and filling your databases with your data.

Disadvantages?

It’s online – you couldn’t work with it offline.

But wait, you can export your data – to Excel, for example, edit it and import again, when will have internet connection.
I believe, that in future we will be all connected.

And there will not be a problem to be offline, all be online.

And centralized data centers will become a normal things.

I think it’s interesting, how we can help to grow it now, and to be on the right track.