Cloud storage requires very high uploads to be usable. 1Gbps is ~125MB/s which is nowadays slow compared to SSDs. So you'd need 1Gbps at a minimum and even then it's much slower compared to what's in your machine.
Raising upload speeds would also give an incentive to cloud storage providers to take advantage of them and improve their ingestion speeds.
From a decent VPS I have easily hit 1 Gbps with google, Dropbox and OneDrive with rclone configured well.