> I don't think any designer has cared about that in the last 30 years. Perhaps not ever.
Not true at all. For instance, Arial was/is typically used as the fallback font for Windows users visiting a website that relied on system sans-serif fonts, while Helvetica shipped with OSX and would be prioritized for those lucky users.
Arial would be chosen by Windows users as good enough because they were already locked in a prison of bad design and terrible typeface rendering anyway, and didn't have other sensible options installed by default.
My point is not that font substitution never happens (it quite clearly does). My point is that no print designer has ever thought "yes, I want Helvetica here, and sometimes we won't pay for Helvetica so sometimes it will look like Arial, and this is what I want". Probably back in the days of PostScript built-in fonts and font cartridges some people thought about that. But since TrueType and embedded fonts happened, I don't think a single designer has ever given a shit about these two fonts being metric-compatible instead of just, you know, picking one and designing with it.
Web design is its own beast and any web designer who wasn't designing, from day one, for different fonts possibly being used without even any regard for metric compatibility wasn't doing their job.
Sure ya, but I don't think it was implied that anyone was talking specifically about metric compatibility exclusively for print design though, just "metrics" compatibility for design in general, specifically game UI, which could be other kinds of documents transferred between people with varying fonts and OS installed
Not true at all. For instance, Arial was/is typically used as the fallback font for Windows users visiting a website that relied on system sans-serif fonts, while Helvetica shipped with OSX and would be prioritized for those lucky users.
Arial would be chosen by Windows users as good enough because they were already locked in a prison of bad design and terrible typeface rendering anyway, and didn't have other sensible options installed by default.