I agree, just like the joke associated with podcasts it seems there are more people writing newsletters than those reading it.

I unsubscribed to the newsletters and stopped subscribing to new ones as they just end up unread like you've mentioned in the problem. That means I'm missing out on genuinely good news letters which share knowledge and not just collated information.

The issue as you've noted is  that we have limited time and every single thing on screen competes for that time, On average we subscribe to Newsletters due to the Fear of Missing Out (FOMO) and are unable to make time for it as things which we like more takes precedence on the screen.

This is more of a Time Management problem - /problems/30 and a  Focus problem - /problems/93 than a technical problem.  Perhaps something which can make newsletters less boring and give it a fighting chance against others competing for screen time can help address this problem.