I have a few, I'm sure, but the one that comes to mind is my hatred of PDFs. Or, I suppose more accurately, the things people choose to use PDFs for. If something is not primarily meant to be printed, then a PDF is a suboar choice to something like HTML. Worse, virtually EVERY place you're getting a PDF from is already a website so they already have the ability to give you HTML.

You can create a single HTML file, embedding all images, CSS, JavaScript, etc. directly into the file. Then you can open it in your browser. It works. It's easier to read too, unless you want to print it. I would argue that in the vast majority of cases they actually aren't being printed. And get this, you can actually print HTML files too, ya know. So PDF is really only better if you need to print something with a very specific and strict layout, like a brochure or something.

"But Jackby, I use PDFs and I love printing them"

Okay, that's fine, I just think you're the exception. I think most people open them in browser or some PDF viewer and never print them ever.

My favorite response to this opinion was someone telling me that having all the CSS and JS in one file makes it load slower. Like uh, off my computer? Because I'm talking about distributing the file itself, not hosting it on a website. I think web folks just latch onto best practices for the web.