Question: Why do Cisco and everyone else think the multiverse is destroyed? At the end of Crisis we explicitly saw a "tour" of various recreated earths, like Earth-12 with the Green Lantern Corps, Titans, Doom Patrol, Swamp thing all getting their own, Brandon Routh's Superman being back on Earth-96 in his old suit, etc. Is it just that people assume all the earths were combined because the new Earth Prime is a bit of a mish-mash?
Answer: Exactly, the new series, Stargirl, shows a universe where the JSA existed, but to soon to tell if it's situated on Earth Prime.
Chosen answer: Earth Prime is a combination of Earth-1, Earth-38, and Black Lighting's Earth. However, the Earths in the new multiverse are separated by something other than vibrational frequencies, so Cisco can't vibe them, nor can they travel to other Earths as before. So the Paragons think it's still destroyed and don't know (at this point) that Queen/Spectre recreated some of the other Earth's (and new ones).
Bishop73