> who really cares if “æ” is written as “ae”?

Nitpicking, but if you're writing about text rendering you should know:

Yes, ligatures are really about presentation and not semantics. For example fi (U+FB01) means the same thing as fi; it just looks neater in some situations.

æ (U+00E6) is not a ligature; it's a mostly obsolete character, with different semantics (or phonetics) than ae.

For example, for purely typsetting beauty, your word processor might substitute the ligature fi for the two letters fi (which can f* search, and I resent both the ligature and lazy search function developers). It would never substitute æ for ae; that would misspell the word as much as substituting an o.

> æ (U+00E6) is not a ligature; it's a mostly obsolete character, with different semantics (or phonetics) than ae.

Reading that a letter in my alphabet is mostly obsolete feels really weird. No rebuttal, just a comment.

> It would never substitute æ for ae; that would misspell the word as much as substituting an o.

While that is correct, a lot of other systems actually do this exact substition. If your name contains æ it will be substituted with ae in passports, plane tickets and random other systems throughout your life.

My own username on this website is an example of a similar substition. The oe should be read as the single character ø.

> _lazy_ search function developers

doing non-ascii first needs awareness and then quickly becomes tricky (encodings yay).

getting combining characters and/or homoglyphs right is hard.

and if you're still bored out: have fun with Unicode confusables.txt ...

with this in mind I dare to give them lazy bums the honor of the doubt and rather call them something between naïve and scared.

> mostly obsolete

The Nordic languages beg to differ!