Classic over-engineering. Their approach is just fine 90% of the time for the use case it’s intended for.
Except that it's a list of English keywords. Swearing at the computer is the one thing I'll hear devs switch back to their native language for constantly
75-80% [1], 90%, 99% [2]. In other words, no one has any idea.
I doubt it's anywhere that high because even if you don't write anything fancy and simply capitalize the first word like you'd normally do at the beginning of a sentence, the regex won't flag it.
Anyway, I don't really care, might just as well be 99.99%. This is not a hill I'm going to die on :P
[1]: https://news.ycombinator.com/item?id=47587286
[2]: https://news.ycombinator.com/item?id=47586932