The article claims that you can slice up the video and only use language-specific hardsubs for parts that need it. I'd be interested if there are technical reasons that can't be done.
You can also use the same kind of segment-based playlist approach on Blu-ray if you wanted to, though theoretically you should be able to use the Blu-ray Picture-in-Picture feature to store the typesetting in a separate partially transparent video stream entirely that is then overlaid on top of the clean video during playback.
We did do inlaid server-side ads that way for a while.
IT just takes an excessive amount of work.
The real solution is just the full support of ASS/TTML/VTT subtitles on all platforms. Usually smart devices are kind of only partially supported.
For instance - casting to a chromecast fallsback to SRT.
You'd see playback issues go up by 1000%.
In the nicest possible way, it is pretty clear that this article was written by somebody who has only ever looked at video distribution as a hobbyist and not deploying it at scale to paying customers who quite reasonably get very upset at things not working reliably.