I think it's because there's lots of different food crammed together and people will pick through it to find the bits they want so it just gets into a mess very quickly.
Obviously makes the whole thing unsuitable for people with allergies or anyone who's vegetarian or doesn't eat pork for religious reasons as there's always a lot of charcuterie.
With a cheeseboard you just slice off the cheese you want and take crackers and grapes to go with it.