The theory was less about the pizza place (more of an MSM strawman attack), and more about the use of "pizza" based codewords for pedos in bizarre parts of the Podesta emails
I have to repeat: the specific pizza place (comet ping pong) is largely irrelevant, just like any one of Jeffrey Epstein's properties is largely irrelevant
Most "conspiracy theorists" critical of Epstein pre-arrest did not obsessively focus on one particular place he was linked to, the focus was on his behavior and his networks
Similarly, pizzagate was focused on some of Podesta's networks as well as some bizarre behavior that alarmed people. The behavior and language being used in suspicious ways was the important part
The most important Pizza-related thing was that "Cheese pizza" was a codeword for "child pornography", with various other terms being alleged codewords for other... related things
The inspiration for the codeword is up for debate. One theory is that to avoid getting "Chris Hansoned" that child predators would order a pizza for the location, so they'd get a front-man to "test the waters".
Regardless, Ben Swann did a good summary of it.
Furthermore, this use of "pizza" as a codeword has in fact happened a few times in legal cases on public forums, despite washpo establishment shills argue
What ‘cheese pizza’ means to the Internet’s conspiracy-mongers
By Anne Applebaum
December 9, 2016 at 11:31 AM EST
In the past few days, there have been many excellent accounts of the armed man who showed up at Comet Ping Pong, a Washington, D.C., pizzeria, and the various con artists and purveyors of fake news who inspired him to believe he would discover a secret group of pedophiles in its nonexistent basement. But one detail, supplied by a 16-year-old of my acquaintance, has been missing from many of the “mainstream” articles: the fact that, in some of the weirder Internet forums this particular teenager frequents, “cheese pizza” — a phrase used in one of John Podesta’s leaked emails — was assumed to be code for “child pornography.”
Regardless of whether Podesta's emails used the term in that way, it is a fact that the term is sometimes used as a codeword in pedophile circles.
One legal case of that verbatim happening:
Man busted for child porn after ‘cheese pizza’ Craigslist post
By Associated Press
October 23, 2017 | 1:54am
NEWARK, N.J. — Authorities say a New Jersey corrections officer has been charged with receiving images of child sexual abuse.
Federal prosecutors said Thursday that 37-year-old Stephen Salamak was arrested at his home in Lodi.
Salamak has been suspended with pay from his job as a corrections officer at East Jersey State Prison in Rahway.
Prosecutors say an undercover officer first made contact with Salamak after he posted on Craigslist that he was looking for women and moms “that are into Cheese Pizza,” a reference to child pornography.
After police executed a search warrant on his email, prosecutors say they found an email with five attachments showing nude images of young girls.
The best neutral summary I've seen on pizza-gate was this guy
there doesn't seem to be anything here