Exactly. More people have moved into areas that weren’t occupied much at all in the past. Also, they now declare tornadoes based on computer models and radar, not actually sighted tornadoes.
However, the article clearly states the number Fujita-rated tornados per year has averaged around 500 for as long as reliable records have been kept. The variation is in where and when. Obviously there is more $$ value damage now, as the article explains. (More people with more goodies, and higher population densities in the "new" alley.)
*Note carefully that a declared tornado is not a confirmed Fujita-rated tornado. An official "F" rating (old scale or new scale) from NWS is ONLY determined by ground observation of actual damage. This is NOT the same as your local TV met looking at a radar signature and blurting out "this is a F-1 moving toward such-and-such town." NWS generally does not state F ratings until on the ground surveys are done. They might say "large and dangerous tornado on the ground, moving toward xxx, catastrophic damage expected" in a warning, but, that storm is still not a recorded F rated storm (though it likely will become so recorded after the ground surveys are done.)
One other thing: The article & Mr. Brooks are completely wrong when they state:
"the deadliest tornadoes in U.S. history happened more than a century ago: an 1890 tornado that hit Louisville, Ky. and an 1896 one that devastated St. Louis, Mo. in 1896, Brooks said."
By a considerable margin, the deadliest tornado in U.S. history was the Tri-State tornado of 1925.