Not another one of these... I'd be into them if they integrated with standard protocols and file formats, e.g. caldav, carddav, org-mode, etc, and at least provided an API if not integrations with various open source tools. Otherwise I'm not going to have all my important personal information locked up into a proprietary system that may shut down or may be deficient in some annoying way.
"Not another one of these" is dismissive, followed by a laundry list of things you think are important which are specific to your needs but are not specific commentary on the thing being shown, which is what Show HN is about.
My two cents. I reviewed the Show HN guidelines. With them in mind, I found the parent comment spot-on and relevant.
I agree that saying "Not another one of these" is not the nicest tone. It could be improved -- how we treat each other in this community matters a lot. But the substance is useful, and I interpret the intent as consistent with "When something isn't good, you needn't pretend that it is, but don't be gratuitously negative." per the guidelines.
Speaking to the "it's my data" theme, there is at least one additional comment, which I also find useful, asking "What happens if I try this, come to depend on it, and you shut down for some (probably very good) reason? Will I be able to keep using it, or does it die with your severs?"
