My theory is that the high barrier to entry of online publishing kept all but the most determined people from creating content. As a result, the little content that was out there was usually good.
With today's monetized blogs, it is often content for content's sake. People don't try, or they write about topics which they are not really interested in, but did just to have a new post. Or often the writing is bad.
Maybe today's problem isn't the blogs, but the SEO that puts the crap blogs at the top of the search results. Or maybe I'm misremembering and the old content was crap too, or maybe my standards are higher than they were in my teenage years.