'The absence of catastrophe is not evidence of success.'
I think your argument is still stuck about a decade in the past and completely misrepresents what the economic warnings about Brexit actually were.
Nobody serious was predicting that Britain would become an economic wasteland overnight or that mass unemployment was inevitable. The argument was that leaving the single market and customs union would make us poorer and less productive than we would have otherwise been, and that's exactly what the evidence suggests has happened.
Of course, we can never know precisely what the economy would have looked like had we remained, but that's true of virtually every economic policy decision you could make. The fact that an alternative reality cannot be proven doesn't mean there is no evidence, or that all outcomes are equally plausible.
Blaming remainers for Brexit's failings is just silly at this point - we had a front bench made up specifically of people chosen for their stance on Brexit, all appointed to the key positions for delivering it - it's ridiculous to say that Boris, Patel, Raab, Gove and Rees-Mogg were being held back by a government full of remainers.
At some point, you have to hold the people who campaigned for Brexit and then governed the country through it responsible for what they actually delivered. We're a decade later, we gave a Conservative government dominated by Brexit supporters five years to deliver Brexit... blaming the establishment, remainers and project fear for it's obvious failing is wearing rather thin by now.