They seem a very inefficient way to consume information, with generally a very low signal to noise ratio

For a long time, I agreed with this sentiment. But as someone who spends not a small amount of time commuting, jogging, going to the gym and cooking, I've replaced a lot of passive consumption of online resources with podcasts.

I like to stay on top of the open-source and Linux adjacent news, and reading LWN while working out can be tough. I've found a few podcasts from members of those communities and listen to them. I keep short notes on my phone for topics that I want to revisit later, and find the show notes the hosts themselves curate to be treasure troves of content I might otherwise pass by. My signal to noise ratio in passive consumption has definitely gone up.

Podcasts like the Longform podcast and Current Affairs allow me to delve into content I'd otherwise have to read about.

I do not find podcasts to be a good substitute for heavy technical content, in the same way I would find YouTube videos or audiobooks to be frustrating formats to consume O'Reilly books.