Why monospaced fonts are not used as frequently as serif and sans-serif fonts, outside coding?

We see sans-serif and serif fonts everywhere, from the web to printed books and newspapers. I'm wondering why monospaced fonts are not popular outside coding context?

Here is a simple comparison I made using Pair & Compare:

We know that for monospaced fonts, letters and characters each occupy the same amount of horizontal space. Doesn't this make monospaces fonts easier to read?