It's one of the very unfair things about Infernals against Abyssals. No one complains when Infernals basically just take a Solar Charm as one Charm in a tree, because Infernal trees are very much not Solar trees and Infernal Charms are very much Solar Charms. Abyssals and Lunars, on the other hand, have a massive problem with being goth Solars and silver Solars.
Or, to put it another way, I can take a Solar Dodge and Athletics Charm for a TED tree, because the Charms in question are clearly being used to aid balance and prevent either person having an advantage, because this is clearly a TED tree which comes off CCC with the theme of "avoiding trouble", and so a flurry breaker and a jumping Charm are totally okay (also, one of them has a repurchase that Solars don't get). But Abyssals have the problem that their entire tree structure is the same as Solars. There's nothing wrong with splats sharing Charms, but Charm tree structures also contribute to the problem for Lunars and Abyssals, because there's just the problem of "Why don't I just play a Solar?".
(And Abyssals literally have that as a major character arc, "I want to just go play a Solar". That's one of the big reasons I oppose Redemption for Abyssals as a thing you can live through - Redemption is fine as the end of your story, but playing as an ex-Abyssal Solar isn't. To put it as a tropism, yes, Redemption does equal Death.)