Two apps that use the a cloud service are google drive and google photos.  I think with google photos it’d be a little inconvenient without the cloud but I think that’s all.  The cloud with google photos allows the user to access their photos and videos throughout any device that they’re signed into.  I think it’s a little different with google drive.  I think if Google drive didn’t have a cloud it’d be detrimental to the app.  Google photos is just picture’s but drive is a users documents, slides etc.  If google drive didn’t have a cloud you couldn’t access them though out any device.  Also without the cloud drive wouldn’t be able to scan for malware in you documents.  The advantages for both of these systems is that it’s extremally convent.  Being able to access your photos and documents with any device, weather it be phone, tablet or laptop is extremally convent.  Also everyone has google and the apps also allows you to save your documents as different types of files which is also nice.  I don’t have security concerns with drive, I know it searches for malware that may have entered one of my documents and gets rid of them automatically.  Photos is a little different.  Google photos doesn’t have anything like that so if someone were to somehow hack into the app there’s no way I could tell.  Also both of these apps allow collaboration on your documents.  With photos you can get someone who also has google photos and share a photo album with them.