Simpler, lighter, cleaner install and maintenance? IDK. There is some "this sparks joy" element for me in getting closer to the source and working without intermediates... Peeling off one layer of complexity.
I also kind of gravitate closer to plain Markdown, if one can help avoid running R on top. One reason is simplicity, with a good example in this thread:
IMO,  Markdown syntax just seems to be some much cleaner than the whole knitr::include_graphics code chunk business.
Another reason is broader acceptance of Markdown. I can take my Markdown doc and use it beyond an RStudio session. Can't always do the same with an RMarkdown post in blogdown (well, I can, but with caveats). And if I need to run an R code on the side to generate a couple of images - I'm kind of OK with that.
Totally, I'm with you on that! It was very easy to start a blog with blogdown while knowing nothing about how to make things work. After a year of prodding, tinkering, breaking and groking things, I kind of done a lot of hugo things directly anyway... That's when I started to find blogdown as a layer of abstraction.
I guess it's the same way with, say, learning R via tidyverse: it gets you started fast, but inevitably you kind of learn some concepts along the way and later realize you don't need to load a package per every line of code.