Although that spelling makes sense, it's not one that's ever been widely used (since 'education' is from French éducation). So I'm not sure if that's an attempt to use a dated spelling (I noticed some others, such as élite) to conjure a certain je ne sais quois, or to forge a new trend for continental accents in English writing where it seems there ought to be?
TL;DR: it was an arbitrary decision from long ago that they stick to despite getting many letters of complaint.
https://www.newyorker.com/culture/culture-desk/the-curse-of-...
Personally I use a diaeresis as well. Not very hard on an Apple device: press-and-hole "o", wait for the pop-up, press 2.
> This was in 1978. No one has had the nerve to raise the subject since.
If it ain't broke, don't fix it.
There's a poster on a message board i read who always uses the archaic letter thorn for 'th' (þink of writing someþing like þis). Whatever a comment is about, 70% of the replies are criticising or questioning the use thorn instead.