They most likely did not believe it for a femtosecond, but it fit their socialist phony narrative so they amplified it. One of the wonderful things about being a leftist in the USA is that you never have to admit you’re wrong. If on those extremely rare occasions you’re actually caught out you simply say “we didn’t go far enough.” And if that is inappropriate and nonsensical you say nothing at all secure in the knowledge that it will be instantly buried by the media.
Same that believed plugs won 2020 legitimately.