IMHO, it's dependability. It's easy and flexible because I can set it up as a web service or use it offline. For the average reader of HN, it takes probably 10 min to set it as web service with npm and reverse proxy + SSL and then you can use it from any device. With a little CSS it can be beautiful and with plugins you can have a connection graph similar to Obisidian. Once it runs, then I don't need to worry about updating it every other hour because of bug fixes and compatibility breaks. And I know it will be there for the next 20+ years.