The best (and most widely adopted) products are mostly accommodating with familiar patterns and rarely “retraining” with something that is entirely new. Only force new behaviors that power a unique value (think Snapchat opening to the Camera while competitive products opened to the feed, etc…).
Great product managers spend most of their time doing research, discovering opportunities in the market, defining the vision, keeping teams aligned, socializing ideas, and getting buy-in and agreement from stakeholders. They are the glue between teams. However, most product managers are terrible.