[twiss]

They may be useful, but they make a language much harder to learn to speak correctly, which is a downside for a lingua franca.

[fkistner]

But so do inconsistent spellings. There is a reason, most languages apart from English have no use for spelling bees. [1]

[1]: https://www.washingtonpost.com/news/wonk/wp/2013/05/30/spell...