I think of blazers as urban, as workwear, as something for an interview or speech. It says "mover and shaker." And with the vast number of blazer influencers on Instagram, you'd think we all had to have one! It is certainly described as an essential.
I haven't had one for years. I live in a jeans and sneakers town (Albuquerque) and I work in retail. I so don't need one. But I love how they look, and might pick one up if I came across it at a consignment shop, etc.
How else would you use a blazer, if your entire lifestyle screams "casual?"