Hi,
Some people like to use a computer for several reasons.
Poor eye sight can be one.
Difficulty in using a small touch screen can be another.
If you have a Mac you can go to System Preferences > iCloud.
You will see that the Messages app nor iMessages are mentioned.
Whilst the iMessages account on the Mac version may well use an Apple ID that is also linked to iCloud the whole iMessages messages system has nothing to do with iCloud.
You will also notice that there is no mention of iTunes, FaceTime or the App Store either.
This means adding additional items to the iCloud servers is not as easy as it first seems.
9:24 p.m. Tuesday; September 22, 2015
iMac 2.5Ghz i5 2011 (Mavericks 10.9)
G4/1GhzDual MDD (Leopard 10.5.8)
MacBookPro 2Gb (Snow Leopard 10.6.8)
Mac OS X (10.6.8),
Couple of iPhones and an iPad