These tidbits always have to be taken in the context they've been said in.

Paul Graham is a venture capitalist in a hyper-connected society, where pretty much everyone can read and write.

When these ancient philosophers preferred oral exchanges over text based communication you've to realize that text wasn't quiet as easily produced and consumed in their society and what they were likely going for was a fluid exchange of ideas, which was pretty hard to do with written words in that age.