inputenc is no longer needed?

Question

by mistake I noticed that my text (UTF-8 encoded, contains german special characters ä, ö, ü, ß) is compiled without errors although I forgot the inputenc (\usepackage[utf8]{inputenc}).

Here is a minimal example in which the special character "ö" are correctly placed in the PDF document.

\documentclass{scrartcl}
\begin{document}
Heute ist ein schöner Tag.
\end{document}

How can that be? Also here is my log file

>pdflatex text.tex
This is pdfTeX, Version 3.14159265-2.6-1.40.21 (MiKTeX 21.1)
entering extended mode
(text.tex
LaTeX2e <2020-10-01> patch level 4
L3 programming layer <2021-01-09> xparse <2020-03-03>
("C:\Program Files\MiKTeX\tex/latex/koma-script\scrartcl.cls"
Document Class: scrartcl 2020/09/21 v3.32 KOMA-Script document class (article)
("C:\Program Files\MiKTeX\tex/latex/koma-script\scrkbase.sty"
("C:\Program Files\MiKTeX\tex/latex/koma-script\scrbase.sty"
("C:\Program Files\MiKTeX\tex/latex/koma-script\scrlfile.sty"
("C:\Program Files\MiKTeX\tex/latex/koma-script\scrlfile-hook.sty"
("C:\Program Files\MiKTeX\tex/latex/koma-script\scrlogo.sty")))
("C:\Program Files\MiKTeX\tex/latex/graphics\keyval.sty")))
("C:\Program Files\MiKTeX\tex/latex/koma-script\tocbasic.sty")
("C:\Program Files\MiKTeX\tex/latex/koma-script\scrsize11pt.clo")
("C:\Program Files\MiKTeX\tex/latex/koma-script\typearea.sty"))
("C:\Program Files\MiKTeX\tex/latex/l3backend\l3backend-pdftex.def") (text.aux)
[1{C:/Users/USERNAME/AppData/Local/MiKTeX/pdftex/config/pdftex.map}] (text.aux) )<C
:/Program Files/MiKTeX/fonts/type1/public/amsfonts/cm/cmr10.pfb>
Output written on text.pdf (1 page, 14015 bytes).
Transcript written on text.log.

Answer 1

UTF-8 has been the default (essentially by building in [utf8]{inputenc}) for a few years. Since the early 2018 LaTeX release, see ltnews issue 28