It’s mainly the lack of being able to use the same query on SQL as on other objects, like I described in https://discuss.kotlinlang.org/t/build-sql-query-like-you-modify-a-list/19978 (Added link to OP now).
Yes, Kotlin do have a great support for DSLs. I have used Exposed and really love it, but in some cases it is easier to just handle things like a list with regular list operations, at least when selecting only from one table.