I apologise. I think we are; or at least I am.
I agree that any sync service (or app with internet access) possibly brings with it all of the inherent issues mentioned above.
But what I really meant was that the more apps and sync services a user has running concurrently, the greater the chances are that something will fail.
So if service A works well, adding service B might be detrimental all round.
The OP has iCloud and it works for them. No imperative need for them to replace or augment what already works. If iCloud plays up, then service B can be called on.
Apologies, again, if I have still misunderstood. Just trying to support the OP in making any choice they think best. They are right: there is no need for them to use Dropbox.