I'd agree on the use of serif, but not on the majority of researchers reading research papers on actual paper. Even on screen (and esp. on a good e-reader), I'm still more used to reading serif fonts in research papers.

If I'm going to do more than scan the introduction, I always print a paper. My comprehensive is significantly higher than reading on a screen.

If it's under eight pages I print it out so that it's easier on my eyes.

I bought a cheap Brother black-and-white two-sided laser printer in college, along with a high-capacity toner cartridge. Use a high-quality stapler to put 3 staples along the left margin. I have printed many thousands of pages of articles. I can't recommend this highly enough.

I finally got my hands on some decent e-ink readers (the HD Kobos, when they still had a micro sdcard slot), and it's pretty pleasant to read papers (particularly in natural/external light) using KOreader[0], without having to deal with physically printing them out.

[0] https://koreader.rocks/

I used to, but in the last few years I don't think I've printed out anything.