I think that Parliament's problems are largely due to the fact that "To a hammer, all problems look like a nail".
May has spent the last two years trying to hold her party together, Corbyn's been doing the same for a bit longer, and Cameron/Blair/Brown spent most of their careers trying to hold their parties together and picking their battles based on whether they can win a majority or not.
Keeping the party together is their job, and the job of senior ministers is to keep the leader happy and not get on the bad side of other influential party members.
MPs have absolutely no fucking experience of international trade and actually running a country. That's the job of the civil service.
So when faced by a disaster like no-deal-Brexit, they turn inwards. Brexit is such a huge complicated issue that it seems insurmountable and politicians just fall back on what they know. Improve your position in the party and don't lose the support of your constituents (if you're in a marginal seat). Try to outmanoevre your rivals, both in-party and in the other parties. Let someone else deal with Brexit.
I think we'll get a return of May's deal with minor changes to the political declaration. Fuck knows if it'll pass this time. I suspect not, since MPs won't want to lose face by changing their mind. Labour will see a no-deal by a Tory government as better for their prospects in the next GE than a deal that sees them looking like extremely weak and cowardly losers as they back down and let May win the vote. The SNP will oppose any deal. The LibDems know how badly they got burnt last time they supported a Tory policy, so they'll oppose the deal. The DUP are fucking insane and won't ever back down. The ERG welcome the chaos to get jobs as advisers/owners of investment banks and asset-stripping companies, or they are just concerned that the deal specifically requires the UK to implement planned EU tax-avoidance laws that could reveal links to dodgy companies in the Caymans.
