Thank you, Gizmo, for the clarification!
Yes, I agree, <i>, <b>, and <u> should not be used.
From my understanding, using <em> when selecting the italics option and <strong> when selecting the bold option and <blockquote> for quoting however would be in line with modern HTML practices and standards. They are meant to convey semantic information.
The important part to notice here is that the browser's focus/reader mode simply does away with the CSS information and only interprets the HTML. When reading text in a UBB forum via reader mode, this semantic information is then lost (
https://www.w3.org/TR/WCAG20-TECHS/H49.html)
I believe this would help people using mobile devices as well as people with disabilities.
Thanks, Michael