Explicit variance, especially for types, is just really confusing. Implicit variance has the risk of breaking APIs or overpromising a particular variance withou

Explicit variance, especially for types, is just really confusing. Implicit variance has the risk of breaking APIs or overpromising a particular variance without developers realizing. If you have subtyping you need to think about variance. That's led me to believe that subtyping's simplicity is deceptive, and that it should be avoided as much as possible. (Rust has subtyping but only for lifetimes, and it's confusing enough there.)