I see many examples of personal tech blogs that use a monospaced font for all the text on the website, including long blocks of prose. I would guess that this is most commonly done to convey a sense that the blog is “minimal”1 or “technical”. The problem with this is that it prioritises an aesthetic choice over the readability of the site. It’s fine to want your site to be aesthetically pleasing, but this shouldn’t actively impede the process of reading it.
See Practical Typography’s page about monospaced fonts for a better explanation of the problems with using monospaced fonts outside of code listings.
This is one of my strong opinions about website aesthetics and design.