It does make me wonder what a tool closer to the Unixy end of the spectrum ("mechanism, not policy") might look like, but I can't fault the guy for having a clear aesthetic vision and a determination to limit scope creep.
I think the model for sharing data between cards is that you put the data in a field, then you can access it from anywhere with `deck.cards.cardname.widgets.fieldname.value`. If you don't want it to be exposed to the "user", you can make the field invisible, or just stick it on a "global variables" card that no other cards link to. This is a bit like, on a spreadsheet, hiding your data in the ZZ99 cell.
For a Product, that's not enough, you need to keep the implementation hidden behind the interface. But I don't think that's what Decker is going for; one of the taglines it shows at startup is "an interactive sketchbook", and I think the Brutalist exposure of the inner workings is part of the point.
