As an outsider, it surprises me that those in leadership positions wouldn’t prioritize feedback and guidance from team members rather than relying on a quadrant list from a market research firm.
The Magic Quadrant (and other similar products) act as a conversation starter and product validation that can give the buyer some confidence that there is some semblance of support, because their ass is on the line if a product they bought turns out to be garbage.
Edit: added additional context
The reason I use this is because it helps me to easily identify potential vendors and products that can help me achieve the goals of my company.
The Magic Quadrant allows me to see how different companies compare to one another in terms of their position in the market and how they perform compared with their peers. The quadrant also includes a brief description of each vendor or product so that I can get a better understanding of what each one does before deciding whether or not it would be beneficial for my business.