that "somewhere" you read is totally correct. Spheres make sense for warships because they have the smallest targettable cross-section ("shadow") for the relatively largest volume. You can pack the most machinery inside. Also spheres are sturdy. Take a hit at one point, and the forces distribute evenly through the shell.
If going to war is not a consideration, many other configurations are definitively easier to build.
In the real world, dumping waste heat is often going to be a problem. (Go go /sci/ to discuss why, I'm not going to explain here.) Which means those "sails" might not be solar collectors but radiators.