This really deserves to be echoed. Accessibility just isn’t taken seriously by web developers in general and it makes me so sad. If it’s mentioned at all most of the time it’s an afterthought and they try to shoehorn it in on existing code as an afterthought which just makes things worse.

I want to implore everyone on HN to not be one of those people

Why is it so bad for accessibility? I don't know much about web design.

Browsers, and therefore things like screen readers, see table elements as collections of tabular data. Using these elements for layout or design will cause a confusing and useless interpretation for people using a screen reader or analogous tool.