Dumb databases? I hate that. It's all in advertising and marketing muscle. Some systems use database as storage only. No constraints, no procedures, no views, no triggers. This is silly. And they claim 100% portability to any sql server. You don't an sql server at all for such purpose. Constraints are not fully portable, so they're not used.
I could not agree with this more. Portability to multiple databases is almost never an advantage for business software. Most customers in most verticles don't care. Most such claims are hype with no real requirements behind them (and they probably don't work very well, either). And no constraints? At all? Once again, this is not dumb database, it is stupid database.