I wouldn't go as far as to make absolute statements like that, but a plan, a roadmap, a schedule if you will, can provide not only a sense of purpose but also a north star to the team, to remind them where they want to go or what the ambition/achievement is. In parallel - No founder will get investment without having a plan and consequently no VC will give funding to someone that is not able to articulate some type of (business) plan to make his/her business profitable.

Agile/SCRUM was taken too far out of context to convince people that it is a framework that works. It works, it definitely works, but not thanks to radical statements (and mindsets) like "if you follow a plan you will fail".