[Aloisius]

They have different QoS levels.

Steam Cloud is truly a backup service. It's not fast even for tiny amounts of data. They'll even kick you over to an even slower lane if you store anything over 250 MB.

Meanwhile, you can do near real-time app synchronization over iCloud between devices.

But yeah, it'd be great if Apple bumped up the free tier size. That said, I've never actually had any problems storing app data on iCloud. Apple users seem to either pay for more storage or not backup to iCloud, so from a developer perspective, eh.