RMC and Sunday Buff

I have seen a lot of comparisons between RMC and Sunday when it comes to supporting Castorice. People fight day and night over this topic and it is never-ending.

But this post isn't about who is better. Instead, I want to understand why RMC buff when targeted to Castorice extends to her Memosprite even when the dragon isn't summoned yet whereas Sunday's buff while a dedicated support for Remembrance units isn't doing the same?

What's the difference? Shouldnt hyv clear this first?

When they released Sunday, they marketed him as the limited support for summoner and yet he is clunky in terms of buffing memosprites. I have no issues with his Ult not providing energy for Castorice. It is normal because we have Acheron and Feixao having special energy mechanic. However his skill and ult buff when targeted to Castorice should extend to the memosprite even if the memosprite is not yet summoned just like RMC. They do the same thing which is buffing a character. One extend to memoprite, the other doesn't. Like why??

Feels like this is a scummy move from hyv.

Or maybe I am wrong. If someone who can explain why such different mechanics exist in the game, please feel free to educate me.

Thank you.