[ahachete]

Fair enough. Yet it might be difficult to summarize the tradeoffs succinctly enough for a title.

"Harmful" conveys enough information to raise awareness of a topic which might not be usually considered. Both examples show this pattern: schema-less is often considered a good thing, when it is not (in Stonebraker's and my opinion); also subtransactions are usually considered a good thing, while the OP shows they can have notable negative effects (of diverse nature) in the database.