Imagine if I had to store the 50k+ tweets I've made on Twitter on my device, and upload ALL of them to a new server whenever a community server went down. Imagine being a server admin having to deal with people uploading tons of JSON data and media a whole bunch at a time. And if you're implementing the protocol correctly, EACH JSON BLOB REQUIRES VERIFYING THE SIGNATURE!! So you'd have to do 50K SIGNATURE VERIFICATIONS! WHICH IS CPU INTENSIVE!!! AND SLOWS DOWN THE SERVER!!!