Now before I reply to this I do want to make something clear, I p,ay a single save which reaches to about day 670, so i follow the storry then do mess around a lot with my favorite scene so i can forget some things.
A lot of what people attribute to Rae is the main story. Her teaching the MC to etherwalk and all of that, as well as pushing out, reaching out to people, and trying to work out what's happening.
Now this i did attribute to main story, but that was also early in the game when we first started out Thats because all this also attributed to them trying to get out out of the house after rae realized she wasn't purposely captured by a extremely powerful magi that she couldn't charm/seduce. Also i didn't attribute the dreams and him grabbing people to her at all, that was more main story stuff to me.
Cait and Lyriel actually do help with the main story (Lyriel senses, Cait overthinks); Cait is meant to help with the whole magic/tradition issue, whereas Lyriel just seems to opportunistically (but consistently) be helpful with her senses. Naomi barely rates a mention in it (with the 'I felt it too' moment), but given even the smallest potential there, she may actually be more useful later.
Now this is where we may disagree... Cait is suppose to help with the magic issue yet she can't do that because she herself is barely a mage. I guess she is shown at some points as someone who is suppose to be skilled or a prodigy but it doesn't really shine through half the time and it gets even worse when rae starts teaching her magic because that just shows rae can teach you as well... which she had already started doing to begin with. Then add onto the fact the house can produce things at will or instinctually by the player... really there is no reason or one I don't remember why he couldn't produce the magic books he needs to study.
As for lyr I honestly don't remember he senses be helpful outside of hearing the strings snap or that one time outside in the woods and if memory serves, the player also felt something was off/wrong then too... I think when they looked into the portal she felt like someone was looking back... but that really added nothing to the main story.
As for Naomi lets be honest here, her whole role is going to be to beat someone up which won't add much seeing how rae is also a trained warrior and lyr is a trained archer and now we got Yona....
As to Yona and Blair, remains to be seen if they contribute anything at all. I can see Blair's crystal-related whatever becoming more relevant to the mystery, and her limiting understanding being a factor. No idea what Yona brings to the table yet.
We can agree they've added nothing .
I'm not sure if you've missed an update here.
No I didn't miss, just forgot it, but the part of the mc vast potential isn't fake though because we see other characters that should be able to call it out if it wasn't even acknowledge him.