In my experience, when you're in the "invention phase" is when it's most critical and beneficial to have and demand more discipline around your output artifacts. Precisely because keeping context and content around your fast iterative decision-making and implementation phases is critical to avoid wasting time on duplicated effort or needlessly repeating mistakes over and over again.
Literally every situation I've ever seen in 20 years across all manner of marketplaces and every imaginable stage of development has had the immediate faux-gains made from ignoring spending 10%-20% more time now (to produce something at least coherent, commented, and composable) ultimately overwhelmed by the soon-to-be-immediate costs of having to live with the consequences of the dubious "shortcuts" taken.
I agree with you that it's extremely hard to achieve maintaining that kind of discipline when under the gun, but that's a people management and expectations problem, not an engineering effort problem. I'm 100% certain that in any given window of time, no matter how crunchy that crunchtime is, that if my team spends 10-15 out of every 100 man-hours producing a higher-quality "minimally acceptable" artifact that they'll both materially accomplish more in that first 100 hours than if they'd spent all of it hacking together a barely working dumpster-fire in the same window of time, and that it will pay glaringly obvious dividends for their productivity in the next 100 hours after, and the next after that, and so on.
Lacking that discipline is neither a necessary condition nor a near or long-term benefit to a prototyping or product development cycle. It's purely a function of leadership, expectations management, and experience.
(I'm even giving the benefit of the doubt that what's being done "hasn't existed before", which is overwhelmingly not the case. More typically it's different people and different teams just painfully learning the same hard lessons in parallel, often because there's an assumption/delusion what's being done is a legitimate pioneering effort instead of the probable reality that it's really a minor variation on something else that already has well-established successful models available to learn from and mimic.)