There's legal red tape that can matter, for one thing. Any third party you use for this sort of thing potentially needs to sign a Business Associates Agreement

There's legal red tape that can matter, for one thing. Any third party you use for this sort of thing potentially needs to sign a Business Associates Agreement with you that ties them in responsibility to your commitment to HIPAA compliance with your users... So there's at least some value to add in being willing to take on that level of legal responsibility. There's also some value in a service run by folks who know the ins-and-outs and can help abstract or educate users. I meet lots of folks who want to write apps for healthcare but are terrified to wade into the murky regulatory waters. I've no experience with this particular service, but I do think there's room for vendors like this. [background: developer in healthcare for 10+ years]