Every database, index, finding aid, etc. has one “pitfall.” There may be a small portion of records that are missing. There may be a location whose name is spelled wrong in the database. The search screen may not work quite like other search screens you use. Every name listed on every record may not be in the index.
If all you can think of are the “pros” it may be the “cons” that get you.
Being aware of pitfalls does not mean you are focusing on the negative. It means you are aware of the limitations of the finding aid.
And that makes you better able to use it appropriately.