A “big rpg” is possible full blueprint developed, but the team must be very good programmers.
And very good programmers work faster with a text editor so there’s no point for them to go full visual scripting.
Blueprint is slower just like Java or C# so your mistakes will affect performance much quicker… Btw at least you won’t be able to generate memory leaks yourself, in C++ you will. Memory leaks can destroy your project and you may take months to understand where the problem is.
Both sides have its ups and downs.