Yeah, I'm not buying the filler argument (especially when in this case, it makes no sense - this is not an adaptation of another work that needs to stretch the episodes waiting for new content).
Each of the gems got the spotlight turned on them for an episode, showing how they are dealing with the fallout of what happened in Call for Help while separated from each other.
Garnet, being that she's a fusion, had a passionate argument between Ruby and Sapphire, which makes sense because they have each other.
Amy and Pearl, however, have no one - except perhaps each other. They don't want to dump this on Steven, but the Gems didn't appear to be on the best of terms still. So Amy gets to talk about it and reunite with an old friend, and Pearl - who is staring into space on the couch in Steven's home, deeply lost in thought probably because she doesn't feel welcome in the temple right now - gets a pep talk and also gets a distraction in rewriting the play - giving her a chance to feel in control of something again, because that's her nature - and then spend some time out of the temple to watch it, beaming with pride at her "son".
Was it a quiet episode? Sure. Not as emotionally heavy? No doubt. But was it filler? I don't think so.