it's because we have limited ability, not all people have good knowledge to make quality content, and not good knowlegde people can produce a lot of quality content. Because sometime people need inspiration to make it.
So, it's not strange when you find there is a blog which contain all quality content but updated slowly, maybe there is only 1-2 update per month, it's not because the blogger lazy but their are in searching for inspiration/maybe in doing research for their next article.
But if you wanna find quality content, but have no ability to make it, you can search for content writer, this is most common advice. There is one more alternative, just buy content package (ready stock), i find content sell on
HERE is good quality.