Wisdoms There are of course several reasons but C2 is often excellent on its own. Some project that I have built has been completely dependent on plugins. Overall, I only use plugins when I have to squeeze C2 beyond its borders.
This, however, C2 handle with flying colors as we see in the tutorials you link to.
Another reason is that it takes a lot of time to test that everything works in exporters. C2 default plugins are often verry well tested, tested