"Can be" does not mean "is". Unless it is built to do so, why expect it to? You have no idea what they're running, nor on what kind of machine or bandwidth allotment, why are you making these huge assumptions and insulting people who don't meet them?
Why? Maybe they optimized for their own performance (put words online) instead of (buying, configuring, and) over-building their server. What if they're not a sysadmin? What if they hate sysadmin work? Seriously, it's a wordpress site.