Regardless of what goofy market-speak business model hoodoo-voodoo is allegedly being used, I think what it really comes down to is who you have assigned to what. PEOPLE are what makes the difference, not some goofy organizational plan. To that end letting people do what they are trained for and what they know how to do is how you succeed.
... and that's REALLY a problem with double-talk buzzwords like "waterfall" and trying to strictly keep things "flowing" top to bottom. The people at the bottom usually just get crapped on thanks to the people higher up in the organization not even knowing enough to be making certain decisions.
I see it all the time where you have the marketing/salespeople who don't know enough about what the coders can even do to even be talking to the customers. They up-sell the impossible, under-sell the possible, and promise a sky that can never be delivered. You end up with upper and middle managers who couldn't code their way out of a piss soaked bag with a hole in the bottom saying "You're gonna use these framework" regardless of if they even apply to the project at hand or are any good, just because they read about it in Forbes or some "professional lecturer" pulled their Jim Jones routine at one of those circle-jerk echo-chamber "developer conferences".
At BEST concepts like "waterfall" or "agile" are nothing more than trying to come up with one all-reaching unified plan for every situation that ends up fitting none. At WORST it is just more of the industry's penchant for bullshit bingo.
I've been programming for 40 years, 32 of that professionally... I've seen this BS before under different names, we'll likely see it again in a decade under all new names. It's still the same double-talk "execuspeak" bullshit so common to academic settings and boardrooms that just gets in the way of what's REALLY important, delivering results.
Which is why any REAL businessman would see right through it in a second for the effete "talk the talk but can't walk the walk" nonsense it really is.