Narrative reviews (sometimes called a topic or literature review) are general discussions of a topic, often with no stated hypothesis. They are often invited papers written by experts in the field.
They can provide rationales for future research and can speculate on new types of interventions available. (Ferrari, 2015)
A narrative review is not a "less good" systematic/scoping review. The aims and methodology are different; they are different study types.
Rossella Ferrari (2015) Writing narrative style literature reviews, Medical Writing, 24:4, 230-235, DOI: 10.1179/2047480615Z.000000000329
Some limitations of narrative reviews are that they often do not include methodology (i.e., how did they get these results?) and therefore can be subjective in study selection, which can potentially lead to bias. This also makes narrative reviews not reproducible. Because it is not necessary for a narrative review to comprehensive, it is often difficult to discern how much weight to apply to their claims.
However, narrative reviews can be important and necessary contributions to medical literature.
It's very important to remember that not all research questions require or are appropriate for a systematic/scoping review (SR).
Because there are no formal guidelines that narrative reviews must adhere to (such as PRISMA for systematic reviews) their quality can vary greatly. However, there are some resources to help you build your review.