Totally irrelevant. The response to Dropbox you describe was "meh, easily done with existing tools". The analog hole response is "no app can provide what users would assume this app provides"

I think the comparison to Snapchat is more relevant: Snapchat is expected to provide only temporary access, but cannot guarantee that. This did not impede snapchat's growth, and might not really be an issue for rumuki; however, the use context is different so the comparison is not very informative.