learning a language is hard. Unlike with PLs, learning a language in a vacuum for your own use is ... pretty difficult and hard to apply? And on top of that the

learning a language is hard. Unlike with PLs, learning a language in a vacuum for your own use is ... pretty difficult and hard to apply? And on top of that there are many "good enough" solutions. English has a bunch of weird and confusing issues. But "English as a second language" is at least a variant that is stripped down, with far less weird idioms, and lets you get points across to people. "Correct" pronunciation (whatever that's worth) is also optional. Hard to beat! I thought Esperanto did have some success though! And FWIW I think many language learning communities can thrive on a bunch of people using their second language. So maybe if someone makes a fun synthetic language it can totally work!