The major commercial publishers (e.g., Springer, Elsevier) do publish both PDF and HTML versions of articles, so the end format is either.

I know that we still need to use paper as the medium here and there (we call papers as papers, not files), but isn't that only in that case that we should learn typesetting system?

The need to learn typesetting programs such as LaTeX is field specific. Furthermore, the need to learn LaTeX can be circumvented by learning markdown-based languages like R Markdown or Quarto. Both of these can be compiled to many outputs such as HTML, ePub, PDF, and MS Office formats.

If the author doesn't care what medium the intended audience will read on, then why not using web format, as I think it is more popular these days?

I would challenge this assumption. Popular among who? Web developers? Data scientists? Academics? The general public? Most non-academics I know use Word and even most academics in my field use Word to write documents.

Or is it just that the new medium needs more time to widely adopted? In that case can we expect that more journals will accept web format submission in the future? Or if not, then what makes us expected that the intended audience will read the papers on papers?

I encourage you to push your envelope and expand your horizon. Specifically, explore how other people publish who do not follow the traditional methods. Tools like Quarto allow people to write in one language and compile to many other languages. Examples include

• R for Data Science that is both an author hosted website and a Book from O'Reilly Press
• Python for Data Analysis that is both an author hosted website and a Book from O'Reilly Press
• Modern Dive that is both an author hosted website and book from CRC Press
• Many other book coauthored by Hadley Wickham that are listed on his website
• The Quarto GitHub repo for journal articles
• The rticles package for R Markdown

For your last question:

Why aren't more papers written in web format?

How do you know how papers are written? You only see the output from journal. Most people I know and work with use MS Word. This is neither a web format nor a typesetting program. Personally, I try to use Quarto. Most mathy people I know use LaTeX.

Several major commercial publishers (e.g., Springer, Elsevier) do publish both PDF and HTML versions of articles, so the end format is either.

I know that we still need to use paper as the medium here and there (we call papers as papers, not files), but isn't that only in that case that we should learn typesetting system?

The need to learn typesetting programs such as LaTeX is field specific. Furthermore, the need to learn LaTeX can be circumvented by learning markdown-based languages like R Markdown or Quarto. Both of these can be compiled to many outputs such as HTML, ePub, PDF, and MS Office formats.

If the author doesn't care what medium the intended audience will read on, then why not using web format, as I think it is more popular these days?

I would challenge this assumption. Popular among who? Web developers? Data scientists? Academics? The general public? Most non-academics I know use Word and even most academics in my field use Word to write documents.

Or is it just that the new medium needs more time to widely adopted? In that case can we expect that more journals will accept web format submission in the future? Or if not, then what makes us expected that the intended audience will read the papers on papers?

I encourage you to push your envelope and expand your horizon. Specifically, explore how other people publish who do not follow the traditional methods. Tools like Quarto allow people to write in one language and compile to many other languages. Examples include

• R for Data Science that is both an author hosted website and a Book from O'Reilly Press
• Python for Data Analysis that is both an author hosted website and a Book from O'Reilly Press
• Modern Dive that is both an author hosted website and book from CRC Press
• Many other book coauthored by Hadley Wickham that are listed on his website
• The Quarto GitHub repo for journal articles
• The rticles package for R Markdown

For your last question:

Why aren't more papers written in web format?

How do you know how papers are written? You only see the output from the journal. Most people I know and work with use MS Word. This is neither a web format nor a typesetting program. Personally, I try to use Quarto. Most mathy people I know use LaTeX.