This, a hundred times this. There were endless discussions on Radio 4 (before I abandoned it when I heard Saint Boris say "we must squeeeeeeeeeeeeeeeeeeeze the brakes" once too many) on "will we have rolling lockdowns every winter?", as if trying to soften us up for the idea. This is exactly why I and many others thought it was important to resist lockdowns from the start, in case they become a regularly used tool. Sunak claims that he personally stopped a fourth lockdown, flying in to do so; I don't know if this is true. Certainly Partygate made it much more difficult politically for any more lockdowns or restrictions to be imposed, at least for now, while people are still angry. Without Partygate, we might still be having winter restrictions every year, or mask mandates from "October to Easter".
I have a theory that Partygate might have been deliberately staged to turn the public against further lockdowns; the government knew that lockdowns would cause massive damage, even if they couldn't possibly say so. They didn't even want to impose lockdown at all in 2020, but the scientists and the public were begging and pleading for it; so I think it's possible that a staged Partygate was "behavioural science" to reverse the public's want for lockdown, perhaps bribing Saint Boris with a few million to play along; after all, that government thought nothing of wasting vast amounts of public money, and for him, any publicity is good publicity. It's just my theory, and it might be completely wrong, but the timing of Partygate seemed too good to be true, and it was scrutinised in such forensic detail. (I think the same scrutiny should have been applied to Tony Blair's weapons of mass destruction.)
As for "did Covid exist before 2020"? I think I might have had it in December 2019, when the narrative was "it's nothing to worry about": for a week, I was ill like I'd never been before. A family I worked with in 2020 said the same thing, they all had it in 2019. And when working with that family, I had to carry papers in my car for "permission" to be out and about, in case I was stopped by the police. We must NEVER forget that this became a reality.