This all seems like a re-hash of the top-down vs bottom-up arguments from before the 90’s (which were never resolved either).

There are two extremes, having everything you do planned up front, and literally planning nothing and just doing stuff.

The power of agile is supposed to be "I don't need to figure this out now, I'll figure it out based on experimentation" which doesn't mean nothing at all is planned.

If you're not planning a mission to Jupiter, you don't need every step planned out before you start. But in broad strokes it's also good to have a plan.

The optimum is to have some recorded shape of the work to come but to give yourself space to change your mind based on your experiences and to plan the work so you can change the plan.

The backlash against waterfall is the result of coming up with very detailed plans before you start, having those plans change constantly during the whole project requiring you to throw away large amounts of completed work, and when you find things that need to change, not being able to because management has decided on The Plan (which they will decide something new on later, but you can't change a thing).

For some decisions, the best time to plan is up front, for other decisions the best time to design is while you're implementing. There's a balance and these things need to be understood by everybody, but they are generally not.