Not so much a 'build it and they will come', more a 'built it and it's marketing's problem now'
Disproof
A clear G2M that has been agreed with the people doing the going to market, even if those people sit in the product team and just buy facebook ads
Consequences
Your product, being not used, delivers no value. No value, no money, no jobs. You’ve succeeded at not building anything, just with more steps and money burnt
Marketing, flying blind, starts making shit up and burns cohort after cohort of leads (and most of the cash budget in the case of outbound)
Outbound sales either ‘can’t do their jobs’, or ‘take the initiative’ and start shifting weight. You’ll end up with the wrong, pissed off users with missed expectations, or very expectant ones that have been promised the moon in custom development
Causes
At any reasonable scale there will be someone whose job it is to not make the product, but to get the product into people’s hands.
Such a person is somehow assumed by the product team to be omniscient. This leads product to stop putting any thought or, god forbid, effort into it
This person is not, in fact omniscient and tends to do badly because they’re piecing together the target user and intended value of the product, etc. from the totally unorganised transient chicken scratch that passes for documentation /(which anyway omits half the key decisions given they were made in the pub after work one week/)
Approaches
What needs to happen is entirely dependent on who your users are and how they need to be communicated to
Whatevery particular way your product needs to meet users where they’re likeliest to actually use it, make damn sure you’ve signed off on it
Don’t necessarily do it, but make sure it’s done