I completely agree with this. But there’s often some misunderstandings as to what elements are capable of moving a story forward.
Most people think of plot movement, which is like the skeleton of a story. It’s the structure that holds everything together, otherwise your story is just a mass of flesh and gooey gross body fluids of conversations and thoughts. These things are just as important unless you like a skinny book. Not me. I love a fuller story. But as in life, too big can be… unhealthy. Long, repetitive conversations to fatten up a book are not entertaining.
As with all elements in a story, balance is key. Plot points need to be clear and often enough to keep a good story flow. Having several chapters of characters talking and thinking can be hella boring. Trust me. I’ve read my fair share of boring chapters that lead to nothing. I love character building, but there’s a limit.
On the other hand, a character has to realise something before they can make their next move in the plot. That means dedicating a scene or two to the characters where “nothing” happens. But in actual fact, it does. People process a lot before they come to a decision or realisation about their life or situation that leads to action. This needs some attention in your story for their actions to make sense.
There’s also internal conflict in characters that inhibit their actions. Their fears and insecurities might hold them back from doing something. Without establishing these insecurities through character building scenes, their lack of action makes no sense.
These are all valid things that move the story forward as long as they don’t drag. Sprinkling some well-placed character-building scenes can give your story the meaty parts to satisfy hungry readers.