No one is "obsessing" over anything. Reality is there are very few cases where you can use a single 8-bit character set and not run in to problems sooner or later. Say your software is used only in Greece so you use ISO-8859-7 for Greek. That works fine, but now you want to talk to your customer Günther from Germany who has been living in Greece for the last five years, or Clément from France, or Seán from Ireland and oops, you can't.

Even plain English text can't be represented with plain ASCII (although ISO-8859-1 goes a long way).

There are some cases where just plain ASCII is okay, but there are quite few of them (and even those are somewhat controversial).

The solution is to just use UTF-8 everywhere. Or maybe UTF-16 if you really have to.

Except, this is a response to emoji support, which does have encoding issues even if your user base is in the US and only speaks English. Additionally, it is easy to have issues with data that your users use from other sources via copy and paste.

This is naive at best

Here's a better analogy, in the 70s "nobody planned" for names with 's in then. SQL injections, separators, "not in the alphabet", whatever. In the US. Where a lot of people with 's in their names live... Or double-barrelled names.

It's a much simpler problem and still tripped a lot of people

And then you have to support a user with a "funny name" or a business with "weird characters", or you expand your startup to Canada/Mexico and lo and behold...

Which audience makes it so you don’t have to worry about text encodings?