While this is all true. The fact remains that for a story to be interesting, there needs to be a reason to care about the characters. If a character doesn't contribute to anything, then there is no reason to care about them, since if they weren't there, it wouldn't matter. Frankly speaking, this is my problem with the twins, and I think Taylor is at risk of falling into the same group.
The twins' main purpose at this point in the story is to further Taylor's characterization and act as extra mana/Command Seals. They don't really contribute to planning, they can't contribute to fights beyond being batteries (which is entirely fair), and they don't even feel like they are invested in reversing the Incineration. They aren't so much characters of their own as they are tools for Taylor to use.
Taylor has contributed more by virtue of being more experienced and having her bugs, but as the Singularities progress and the enemies they encounter become stronger and stronger, those virtues are starting to mean less. Currently, I'm most invested in her dedication to Olga, but as that story begins to wrap up, it remains to be seen if that will remain the case.
Ultimately, I need a reason to care about them, and making jokes and monologuing about what the Servants are doing isn't that. I want people, not talking cardboard cutouts. If messing with power levels and letting them contribute to fights will accomplish that, I'm all for sacrificing Type-Moon lore consistency.
Having said that, I don't think that doing so is necessary. Olga's relationship with Taylor is something that I'm invested in, and there are plenty of other ways to make characters interesting beyond making them punch out Gilgamesh.
Rika and Ritsuka are characters, they are Taylor's teammates, the same way the Undersiders and the Chicago Wards were. Taylor is their experienced mentor and leader. Yes the two of them haven't contributed that much to the story in regards to the fights, but keep in mind they have spent several chapters of training, from the simulator battle to their current PT and magic classes with Aife and Waver. They are absolute beginners in terms of being Masters to Servants and mages and are still learning what it means to fight.
But even then, if you only care about characters who are capable in a fight, that's your problem. Stories have far more to offer than just epic fights. Stories are about
conflict. Not fights, not battles, not wars, conflict. Romance is a world famous genre of narrative storytelling, and some of the best romance I've read don't focus on the main character's fight to save his girlfriend from the evil overlord, sometimes the conflict is a nervous boy incapable of telling a lie having to keep the truth about the existence of vampires, aliens, and other supernatural beings hidden. Mystery novels are about a battle of the minds, the perfect crime vs the Truth, criminal vs detective, a conflict which never has to end in a fight between hero and villain. Conflict is about opposing forces, but not necessarily fights or battles between characters. Fights are a form of conflict, but not all conflict comes down to a battle of blows.
Fate isn't a world where humans are capable of fighting Servants. That wyvern Taylor killed in a life or death battle at the beginning of Orléans? There's a reason people freak out about that, because humans haven't been capable of killing wyverns one-on-one for centuries, and she wouldn't be able to fight two at the same time. Even Mash, the weakest Servant in Orléans could do that, far easier and safer than Taylor. Taylor even calls it out, she can't keep getting in fights with these magical beasts and she can't even consider actually fighting a Servant in this world. This isn't a world where brute force can win fights, and she shows it off perfectly at the final fight in Septum. She was able to figure out the true identity of Altera and use it to cause that momentary vulnerability to end the fight, her contribution to a fight that involved fighting so intense and fierce she couldn't keep track of all the blows.
And that's perfect! Taylor isn't a badass because she can suplex dragons into the ground and kill invincible heroes in creative and cruel ways, she's a beloved character because she's weak. And she knows that. People like to 'point out' that bug control like she has is a really good power, but people forget that Alexandria was almost literally invincible, or Legend could turn into light, or Lung could turn into a dragon. Bug control was better than she thought, but it was how she used a fairly middling power to overcome superior opponents that was literally the point of Worm. It was Taylor's perspective as someone weak, having to go up against stronger and more impossible challenges, using her powers and teammates strength in creative ways, always having to figure out a clever solution to the problem, to keep fighting, to keep
surviving, that made her the Hero of Earth Bet that could challenge Zion and win.
Taylor, Khepri, didn't fight Zion, she mind controlled thousands of parahumans to fight him and buy time. She used the Tinkers to make a superweapon to kill him. And she was able to figure out the truth behind Zion's depression and pain and used it to cause that momentary vulnerability to end the fight.
If you only value characters for their ability to directly contribute to a fight, maybe a story about the mundane humans commanding the greatest superhuman legendary heroes of human history against other superhuman legendary heroes and the legitimate monsters and dragons and Beasts aligned against them isn't for you.
And there's nothing wrong with that. Sometimes you don't like the direction a story is going or you get tired of it, and that's fine. You don't have to like this story, especially if it's not to your taste. Don't feel like you have to keep reading a story if you don't like the way the characters grow or the ways they don't grow. If you want a story where the main character keeps growing stronger in order to keep fighting ever stronger foes, go for it. There's tons of stories like that, and a lot of them are good.
