Guardrails are essential. A properly-designed declarative schema change tool provides guardrails to detect and prevent unwanted deletion / drops / lossy conversions. I develop widely-used software in this space (Skeema) and my tool has always offered drop-prevention functionality ever since its first beta release in 2016.

I also argue that guardrails are equally important for imperative migration tools as well, but more often they're lacking or half-baked, which gives a false sense of safety. For example, down/reverse migrations are a very common landmine for human error. Order-of-operations problems also happen frequently when imperative tools are used by large dev teams, resulting in subtle schema drift between environments when there's disagreement between lexicographic migration file order, git history order, and the actual migration application order on each DB.