An alternative thesis - PDFs fit a world view where the highest objective of a document is to be read by a human.
If I am given something that I am personally expected to read thoroughly - be it a report, long-form article, slide deck, etc - then the most professional format by far is a LaTeX PDF.
I can only claim anything beyond personal experience but if I want to signal to someone that a document is important and was written with care then they are getting a PDF.