I don't, but it makes sense to me, I vaguely recall that HTML and XML use a similar methodology and XML is basically nothing but made-up tags.

Biggest caveats I can think of would be to not replace semantic tags (which the article mentioned), and your code could be less intuitive for others to interpret (likely not a huge concern)

i don't use them, they feel wrong to me in a way i can't explain

@skep, Yeah the advice is not to replace the semantic tags, which I don't want to do. Problem is, even semantic tags like "section" and "article" can get really vague really fast when you're trying to figure out what is where. And since I insist on doing everything by hand I want my code to be more legible.

@irony-machine The only thing that feel really wrong to me is that you can use emoji (!!!) in them.

I tried this a while ago with a friend and we were stunned that it worked! but I haven't used them so far

really late to the party but i've used custom html tags myself and they work just fine. in fact, i've used them against the spec without any problems - before i redesigned my reviews page, each review was literally a element. no hyphen or anything, so they're not necessary, but you do run the risk of creating conflicts with existing semantic tags and potentially ones that could be added in the future.

ok it turns out neocities doesn't like parsing element-like text. i meant that "each review was literally a [review] element"