One advantage of LaTeX is that it's virtually impossible to generate markup by accident. This contrasts with other platforms which often decide that I'm trying to create a bulleted list, write something in boldface, etc. -- which hasn't always been the case.

It seems that part of the design philosophy of Typst is to make more assumptions about what the user is trying to do. For example, apparently if the user wants "dif" to appear in a math formula, typing "dif" would instead produce a differential -- although I presume there is some easy way to handle this.

Anyone who has used Typst -- did this potential disadvantage materialize in any way which was at all significant? Or did it turn out to be a nonissue?

This is a nonissue. I've written several lengthy documents mixing up all sorts of pieces in Typst over a year, created my own template, modules, functions...

Text needs quotes in math mode, only single letters are rendered as text.

Markup is indicated by [].

Math by $$

Code by #

Accidentally entering markup mode hasn't happened to me so far.