These keep popping up again and again but are "generally" a terrible idea. At some point you'll need something that you imagined would for sure have an HTML tag and then the misery begins.
What misery? It's not like using something like this means you can only use these styles. It would be very easy to build on this.
For something like a personal website or blog this seems totally sufficient, though maybe a bit boring. I disagree that these kinds of projects are "generally a terrible idea."