Who is incentivized to run projects in the way proposed? Why are teams continuing to do waterfall if its results are so undesirable? For what it's worth, all t

Who is incentivized to run projects in the way proposed? Why are teams continuing to do waterfall if its results are so undesirable? For what it's worth, all the startups I've worked for conducted software projects with the "collaborative" design phase described. From what I understand, large tech companies and "non-software corporations" run projects in the "waterfall-esque" way. Why is that? Surely it can't be entirely meritless, or these companies would not exist for long.