> 2. If you are an end user reading an XHTML file, it's not your file, it's not your fault if there are bugs, and there's jack shit you can do to fix it. You just want the browser to do its best to show you something reasonable so you can read the page and get on with your life.

Here's the thing though, if all XHTML clients are strict about it then that means the content is broken for EVERYONE which presumably means it gets noticed pretty quickly as long as the site is being maintained by anyone.

Compare that to HTML where if a page is doing something wrong but in a way that happens to work in Webkit/Blink while it barfs all over the place in Gecko it could go ignored for ages. Those of us who are old enough remember an era where a huge number of web sites only targeted Trident and didn't care in the slightest whether it worked in any other engine.

There has to be an opposite to Postel's Law that acknowledges it's better in some cases to ensure that breakage for anybody becomes breakage for everybody because that means the breakage can't be ignored.