[asoneth]

Technically it would have been more precise to define "Value Proposition" as "(The result of) a reductive process in the early stages of product definition that...".

Having said that, this kind of syndoche where a process is described by its output doesn't seem particularly unusual or UX-specific. When a coworker says it'll take an hour to do requirements I know what they mean.

I'm not sure why you think "definition" (1: the act of defining https://www.dictionary.com/browse/definition) cannot have stages.

[Blikkentrekker]

Very well, so your interpretation now is that, contrary to what the page itself says, the definition of “value proposition” is rather to be taken the process that leads to a final “value proposition”?

So essentially, your interpretation can be reduced to the advice “It is best to think about what one's product is, and whom it targets, before one makes a proposal about it.”?

If that be your interpretation, then that certainly does not follow from the text, and is contradictory with the interpretations others have given.

[asoneth]

I'm sorry, I would like to help but I can't figure out where you're getting tripped up since (to me) the various interpretations don't seem to differ much in meaning beyond the linguistic/semantic fuzziness that is common in informal communication.