I've never played a single fallout game or even knew the lore besides its post apocalyptic. Loved the show and it was cool as hell learning about the universe. They told the story well and made me care about the characters.
Whats great is that the people making the show really cared about the lore of the games, so if people like you who have no prior knowledge decide to ever check out the games, there isn't going to be an inconsistency with the lore or setting.
The show looks and feels just like the games. Its great, wish more adaptations had writers, directors, actors, etc. that cared about the source material.
The only people spreading this are a tiny subset of rabid New Vegas fans that just read one post about one scene and thinks it deleted the entirety of their favorite game right out of the canon universe of Fallout.
There is a chalkboard explicitly showing "The Fall of Shady Sands in 2277" with an arrow pointing to a nuke, and yet it is thriving and has a 30,000+ population in New Vegas in 2281.
Similarly, the shot of New Vegas at the end shows it completely dead and desolate.
So either, the in universe chalkboard was a lie / red herring and they were teaching wrong recent history for some unknown reason (bad writing), or the chalkboard labeling the "fall of shady Sands" refers to some other event that happened before the events of New Vegas and then Shady Sands gets nuked after the events of New Vegas (in which the case that chalkboard is badly drawn / intentionally misleading, it's retconning that Shady Sands wasn't thriving in 2281, and it's completely undoing the hopeful endings for New Vegas by nuking them out of existence).
Either the Fallout show is retconning the plot of the New Vegas game out of existence, or it's badly written and throwing out ham fisted red herrings while still intentionally undermining NV's narrative themes and hopeful endings.
Todd Howard saying something doesn't magically make it true, you should be aware of that by now if you've ever followed anything Bethesda related.
And again, like I said, the chalkboard clearly shows 2277 in clearly seen chalk. If that is not when the nuke falls, then that brings me back to my other point, that it then implies that Shady Sands started to fall before NV (retcon) and it undermines all the hopeful endings of NV.
I.e. even if it doesn't retcon the explicit plot beats of NV it retcons the themes and narrative.
Have you ever played NV? Because for as much as I love the NCR, being my favourite factions out of any media. NV makes it pretty clear things aren't all sunshine and rainbows.
The chalk board itself is also showing a timeline of events. With the "fall" and nuking being separated. They clearly take place at two different times.
2277 was the date of the first battle of Hoover Dam. If you've played NV you'd know marking that date as an arbitrary "fall" date isn't that far fetched.
Literally the entire date / time setting of the show is arbitrary. If they want to leave the canon of NV intact they would made that date later, though like I said, even if they do that, they're still undermining the narrative themes of NV by nuking the symbol of hope off the map right afterwards.
"No they didn't because I like the show so nuh-uh" is not only a boring an opinion but one backed up by nothing.
As much as I liked the show in general, I think the majority of my enjoyment came from much they nailed the aesthetic, so I'm glad to see people enjoying it so much with out that prior experience.