The difference here is, Roam and similar services run on servers that cost money monthly. The service is almost worthless without it. Ultimately someone needs to pay for this.
The supposed benefit of my data being hosted is not a benefit to everyone. I already have multiple solutions to backup and sharing, I don't need another silo where my data lives. I don't need another vendor hosting arbitrary data which means I now can't use the product because the megacorp I work for won't let that through their legal.
Key point I was making above was that one off payment is an option and can be successful, we don't need to fall straight into the free vs subscription dichotomy.
that is also a downside though. which side of the coin wins depends on the customer. I rather use icloud/dropbox and apps then an unencrypted web version. Roam decided to implement a web app, the actual use case does not require a server or monthly maintanance costs.
No software is really finished.