Wrong concealer shade?

hakuna_matata
I am new in the world of makeup. Yesterday I went to MAC store to buy a concealer (I have some break outs lately). The woman there gave me a concealer darker than my skin tone. When I asked her the reason for it, she told me that a concealer that matches my skin tone won't conceal anything etc etc. so I got these relatively expensive concealer and now when I googled it it says that the concealer should be a shade lighter than your foundation. she did make me wear the concealer for trial and it looked just fine after she powdered it over with mac skin naturals powder or something like that. but now I am wondering whether it was a right decision to get that shade of concealer. its NW 30
Wrong concealer shade?
3 Opinion