[necovek]

I concur — having added it as a third level symbol (AltGr + dash for em-dash, AltGr + Shift + dash for en-dash) to a default layout for Linux in early 2000s, it has become my signature of sorts.

If I am to be called out as an LLM, at least I can lay a claim I've been one for 20 years!

I do eschew one tradition surrounding it — the one of using no spaces around it — despite recommendations of different Manuals of Style and typographic norms. It simply looks better with more breathing room.

[1propionyl]

Would you put spaces around parentheses?

It would look ( to most people ) very strange.

[treetalker]

You know , I have to disagree with you there(but just this time)and I respect your opinion nevertheless .

[necovek]

The most dominant style guide is The Chicago Manual of Style, which recommends against spaces around em dashes, but there is an AP style guide which actually does recommend spaces!

Em-dashes are not the same thing as parenthesis even if they are used in similar circumstances, and as a sibling comment recognized well, you'd still put spaces outside the parenthesis —but this would be terrible with em-dashes— wouldn't you agree?

This is really a style issue, and it mostly depends on what "school" you subscribe to.