Consumer demand and confidence largely comes from how safe people feel in their jobs and whether or not they get raises, not statistics. I'm sure there's some feedback, but my own cautious spending is a direct result of knowing of direct threats to a substantial number of jobs, and seeing the consequences of e.g. potential clients pulling back on spending. I'm not very worried about my own income, but the only reason I'm not very worried is that my disposable income is high enough that I can sustain drops without being affected much.

Meanwhile e.g. my ex. has to deal with knowing that hundreds of jobs where she works will be cut (and no, that's not rumours - she works in HR and has direct knowledge of the plans) as a consequence of Brexit. If the negotiations goes badly, it will be several times that.

That is the kind of things that's causing consumer confidence to soften.

> brexit itself doesn't change the fact there's a short term business cycle driven by credit and low interest rates

No, but it has directly affected that starting to come to and end because of softening consumer confidence.

> capitalism is based entirely on eternal exponential growth, which is clearly not sustainable, there's nothing UK specific about this

No, but there is something UK specific about currently being in a situation where the government has chosen to drastically cut public spending at a time when low salary growth has left people using low credit as a means to keep the party going, and are then suddenly hit by events that cause a great deal of uncertainty over their ability to continue to service debt.