...but the reason "out-of-the-box solutions" exist is because other folks have already spent the millions of developer hours, user feedback, etc to get it working :)
Several years ago I worked for a company (filled with seasoned, smart, great devs) that tried to in-house their own reporting tool
They quit and migrated to Crystal Reports because integrating an existing tool was worlds cheaper/faster than trying to do it all themselves
Later they migrated to BIRT because of CR limitations
And did another migration a couple years after that (I forget now to what tool)
The only drawback from a end-user perspective of those migrations were that reports couldn't be automigrated between reporting platforms
Cube is “headless BI”, which means you still have your own widgets at the front lend, and existing DB at the backend, and Cube sits in the middle helping you combine/filter/group/stat across your tables and other data sources.