Because it was in the headlines several times around the US that some places "accidentally" received saline instead of the mrna concoctions in their vax shipments and that just doesn't happen by accident, let alone on such a scale, unheard of, that was people in the medical field on a local level realizing it was saline followed by talking heads going "whoopsies silly us it was an accident!" and when people started going wtf how is that even happening it was hardcore memory holed, saline would've been cheap af and risk free while making pharma big money too (huge profit margin) while government entities did their power creep, ALL the animals died prematurely in mrna animal trials but then the first try on humans went off with barely a hitch, lol not buying it, most people got saline and small controlled percentage got the experimental shit and got fucked up, plus it helped create a ton of hysteria reactions in the saline crowd making it easier to distinguish hysteria placebo responses from actual mrna effects