Because Congress' intentions are taken into account only after the actual text, and most of the time not at all (or they would have written their intentions clearly within the enforceable provisions.)

I feel like I’m looking at the output of the legal equivalent of “git show” when I tried to read the senate document - first, the commit comment (which does nothing, but does describe intent and list the author), followed by diff style patch script.

Anybody else get that feeling?

It's not uncommon for the intent component of laws to be substantially different than the effects of the actual text. Sometimes because writing laws about complex topics like computer access is difficult, sometimes because the law has some effects Congress would rather not publicly announce. And since the text of the law takes precedence over this sort of statement in court, it doesn't necessarily offer any information as to what changes might actually happen.

Notably, laws like this almost always end up applying far beyond their envisioned scope simply because the landscape changes so fast. The intent of the DMCA or CFAA is substantially irrelevant when major legal cases end up hanging on technicalities in their wording.