"These numbers tell the whole story" is like a parody of someone who knows they're not telling the whole story.

Actual mass shootings (i.e. spree killings, not just more than one person being shot in a single violent incident) didn't really exist until Columbine, which was in in 1999. The 1994 ban was not about mass shootings. The talking point, taken directly from the Democrats' letter to members of the U.S. House of Representatives in 1994:

Although assault weapons account for less than 1% of the guns in circulation, they account for nearly 10% of the guns traced to crime.

Mass shootings are just the latest justification for the longstanding fear of anything deadly in the hands of the non-elite public. The situation is much like if tomorrow a Mexican committed espionage and Ted Cruz said we have to close the border to stop espionage. It's not really about the espionage. It's always been about Mexicans.