They talk of "uncertainty" about how the new customs border on the island of Ireland would work, about whether all the necessary checks could really take place away from the border.
They say there is "uncertainty" about whether this new customs border would undermine the principle of sustaining an all-island economy.
They talk about "uncertainty" about the operation of the single market for goods and food on the island of Ireland, and the proposed new checks on goods and food flowing back and forth between Northern Ireland and the Republic.
And of course they talk about the risk of permanent, corrosive "uncertainty" built into the new arrangements - in the unlikely event they were ever agreed - from Johnson's stipulation that the Northern Ireland Executive and Assembly would have the right every four years to close down the all-Ireland single market.
All of this means that there is zero chance right now of Johnson's offer being taken by EU negotiators into the so-called "tunnel" for the kind of detailed negotiation that could turn it into a ratifiable deal.
Because - in a nutshell - Johnson's offer is seen by negotiators not as rendering the backstop unnecessary, but as demonstrating precisely the opposite, that the kind of uncertainties implicit in what Johnson wants can only be eliminated with an insurance policy that kicks in unless and until Johnson's plan can be demonstrated to actually work.
And that insurance policy is called the backstop.
At the moment, Johnson is asking the EU to have faith in him that his plan will ultimately work, that all the uncertainties can be eliminated, while the UK remains a non-voting member of the EU, that is before the end of 2021 at the latest.
He is saying "trust me".
And the EU's response is "don't be ridiculous".
So the impasse is still there, more or less unchanged from what it was before Johnson even made his offer.
Maybe Johnson's chief negotiator, David Frost, has a rabbit in hat or pocket, to spring on Michel Barnier, his counterpart, this afternoon.
But I doubt it. Partly because the big influence on Johnson, his chief aide, Dominic Cummings, has always said "read my lips, no rabbits, no compromise on the backstop".
Which means Johnson's offer is probably dead, there won't be a Brexit deal to put to MPs, and therefore all that matters now is whether MPs have or can yet obtain the power to delay Brexit and prevent a no-deal Brexit on 31 October.
So believe it or not, the 21 Tory MPs expelled from the parliamentary Conservative party, plus Rudd who quit, today refused to support opposition MPs who wanted to put down an SO24 motion that would have allowed MPs to seize control of parliament’s business on any day between now and Brexit day on 31 October.
Labour and SNP had ordered all their MPs to London to support the motion. But now it won’t be put on the order paper till next Tuesday, if at all.
The point of the motion was to give MPs the power to pass whatever legislation they thought they need to stop a no-deal Brexit on 31 October.
But the Tory rebels apparently now buy the Johnson and Cummings argument that MPs flexing their collective muscles to stop a no-deal Brexit is undermining their chances of getting a deal.
But as I reported earlier, there is next to no chance of the EU accepting Johnson’s offer anyway. So Cummings and Johnson will be chortling into their coffees as we speak.
And business in the Commons today will be of magnificent unimportance.