In reading the report, I was glad to see this stated - upfront. "There might be cracks in space-time, but humanity's telescopes can't see them."
We cannot see beyond the CMBR either and verify what may or may not exist beyond. Just think what may have happened between the geocentric astronomers and heliocentric astronomers, if Galileo told folks there were lights moving round Jupiter - people looked and did not see those lights using the telescope
The report also seems to depend upon the inflation model or flat universe vs. open model.