It's not marketing hype it's real. Sounds like many of the "clipless is unnecessary" folks have not ridden clipless.
The last time I forgot my cycling shoes and rode about 100km in crocs it tore up my legs so bad I could not ride a bicycle for a month, could hardly walk for 2 days. When I go to the grocery in tennis shoes I feel the stress of mis-aligned ankles and knees. Not so with my cycling shoes. I would never ride on flats more than a few miles for fear of significant injury.
Geez it takes about 30 seconds to change shoes , Max. The 1 pr of shoes argument just does not hold water compared to your safety.
That's my experience.