A new player probably have much better use of the RG stones than investing into a girl who offers nothing back to the party.
Rainbow rose is a special case simply because she is an all-in-one package that can carry the weight of 2-3 others, Hosta would not.
Just because a girl has act-again, it's not always a viable choice. (Besides, there are so many other single target act again RG candidates nowadays).
While I understand she's easy to get, general purpose crit buffers should be considered instead if you're just starting out. Otherwise, girls like Dendro Valentine/BB Easter/Hypericum Baseball/Statice and many others can be considered if you insist on having a single target girl with act-again buff.
Black Locust mentioned above is great too, if you don't mind shelling out 615 stones. Bonus point if you RG her base and reskin her to bride.