If you want the best Web App in the world take my codebase (quanta.wiki) and built on top of it. The whole thing is a simple tree structure, on MongoDB, using a 'path-based' tree so you don't even have to learn a specific relational database structuring, and you can put something else on the back end to replace MongoDB. If you like Java+TypeScript+React then I've given you a 250,000 loc head start.
The User Guide and screencasts only show about 10% of the functionality, so you really don't have any way to judge it, but you can still guess can't you.