The good story writing went to the Originals, Stefan was the biggest collateral damage of that.
When I see the first 3 seasons of the originals, I again see good plots like resurrection of Mikael, Ester trying to kill Hope, Strix (could have explored more), flashbacks from the past of Klaus, Aunt Dahlia.... all this could have been shown in TVD because this coincided with season 5-6-7 of TVD which were horrible, it did not have to be that way.
Notice how after the originals began to leave, the plot shifted even more towards Stefan and Damon... now the story is about sire bond, ancient curse bringing them together, Elena having to pick between brothers... all nonsense plots. Villains were bad too post Silas. After Silas we had TVD not even having a real villain with the bad guys in New Orleans and now TVD having Paul Wesley playing Silas. Stefan was the protagonist, he was never gonna sell as an antagonist. They made the universe bringing dopplegangers together to make elena and stefan's story look like fake.
Now have you seen the legacies? I find it to be even bigger BS, the actors are just so bad, Hope herself doesn't look strong at all but we are supposed to believe she is powerful. The actors seem unconvincing.