I am not a fan of 'do this - this is best' response to queries like that.
Rather: this is what you should try, and choose whichever one suits you better.
So, rather than 'natural keys ftw', I am giving him another option to
choose from.
You see, in my world, I was able to improve some large dbs performance
10+ times fold, by going for surrogate keys. But in them cases, joins
were performed on 2+ varchar PK fields, and the whole thing was
crawwwling.
So, don't narrow down to one solution because it worked for you. Keep
an open book.