Sometimes you may want waterfall development; but the luxury will cost you!

Sometimes you simply don't care about the specifics of what comes out the other end of the engineering process. Either because you have high expectations and high trust in what they'll deliver. "High engagement" with the engineering department will cost you time and energy. "Low engagement with engineering will cost you in time and rework, waste, and cost

There are times, like when a business person builds a prototype of a system or clearly defines the product requirements, that they can give that input to engineering to harden and tighten the design. In such a case, the inventor(s) of the prototype or specs may not really care what comes out the other end; their requirements are fundamentally qualitative: 1) Make it look good 2) Make it performant 3) Make it "tight". Managing a project in such a way is possible and sometimes desirable. But there are alternatives.

Not everyone wants to engage with an engineering group in an Agile / High Bandwidth way. They need room and space. They don't want to be an engineer. Weekly check-ins (like in Agile) seem reasonable but maybe some people would prefer monthly, quarterly, or annually. The larger the period between reviews and meetings, the larger the budget, the more the risk, the bigger the problems, the lower the quality.