This is a great trick, but it's only really useful if you're using a CRT or are on a very memory-constrained platform where you can't store a separate 'bold' font.
I've implemented it here https://twitter.com/ViolenceWorks/status/1387519297262477312 and barring the exception of fiddling around with dotclocks and such, it would be far simpler to have a different 'bold' font. Of course, if you're using a CRT doing this is as easy as 'keep the gun on a bit longer if it's bold'.
This is one of the rare cases where you really get to see the relation of a CRT with the thought of, 'a technology is only perfected after it has been rendered obsolete.'
The horizontal pixel doubling as mentioned in the article was a common trick on home computer character sets, which helped cope with the poor horizontal resolution of color TV signals. Though the default font in PC text mode also has a similar appearance which seems a bit harder to explain. Perhaps it was a pure readability concern there, similar to the thick vertical strokes in many printed typefaces.
The PC (5150) wasn't a "real" IBM design, but was developed externally. Even more so, IBM was quite cautious to not put their more valuable assets on risk by this "small" office machine (a strategy, which eventually came to nothing with the advent of the i386 generation). So there wasn't much "trickle-down" and the 3270 stuff was still dedicated to "genuine" IBM assets. You couldn't even run a 3270 terminal emulation. This required an expensive extra card or later a special XT model. – Just consider this: the 5150 was actually some sort of plan B, where plan A would have been to acquire Atari and sell (a possible somewhat improved version of) the Atari 800 as the IBM PC (there are photos of prototypes for the repackaged design by Bill Lowe [1]). Which may also shed some light on what the original specs for the 5150 may have looked like.
I think all CGAs did have that font by default because CGA just had just poor resolution that they didn't have space for better characters.
Most CGA adapters switched to MDA or Hercules mode when displaying text, which offered much better rendering. But if you needed to mix graphics and text this didn't work. So you got stuck with the piss-poor 320x200. And the two hideous colour palettes.
I never understood how anyone could design that and think it was a good idea or something.
I've implemented it here https://twitter.com/ViolenceWorks/status/1387519297262477312 and barring the exception of fiddling around with dotclocks and such, it would be far simpler to have a different 'bold' font. Of course, if you're using a CRT doing this is as easy as 'keep the gun on a bit longer if it's bold'.
This is one of the rare cases where you really get to see the relation of a CRT with the thought of, 'a technology is only perfected after it has been rendered obsolete.'