Each journal focuses on a specific subfield of math/CS/$SUBJECT, so they can make more informed evaluations on the quality of the research than an expert in some other field can.
I mean, seriously, it's 2016. When was the last time you read a paper printed on actual paper?
I know it's not what you meant, but I almost always print out papers before reading them.
> One thinks that underwater basketweaving is overhyped. Another thinks that great work was done in the eighties, but all the interesting questions have been solved already.
Then he cites three general Math journals as what the hiring committee can use to rank the candidates, not a journal specialized in underwater basket-weaving.