Well, I’m certainly in the descriptive camp, so I’ll just describe my experience with the evolution of the language smooshing me and me rolling over and loving it.
I’ve worked in tech support and administration most of my life. So, for the most part I’ve dealt with the linguistical limitations of myself and the other end a lot of the time. Sometime in the noughties, I had someone end a communication with “Please do the needful”. My brain immediately went into adolescent throes of “Oh yeah, if they need doing, I’m gong to do them!”, but I understood exactly what they meant. “The stuff that needs doing to accomplish this, please do it.” It pretty much implied “Unless that will cause a serious problem”, but you had to draw that from context. Sometimes the context implied “I don’t care if it kills you”.
That was my introduction to Indian English, which I soon learned was its own animal. As my “career” has progressed, I’ve gotten to the point where working with people who have English as their second or third language is the norm. Indian English is possibly their third or fourth language, and even that’s probably almost as varied as American/Canadian English when you get right down to it. Others come from different mother languages, and their English has its own inherited idiosyncrasies. “Do the needful” doesn’t even register at this point, other than to note that I don’t see it as often as I once did. It seems to have fallen out of fashion. I kind of miss it.
And in light of all of that, the question I’m most likely to be asked when I’m on a call with someone who speaks English just well enough to not need a translator is:“Where are you from? I haven’t heard your accent before.” I was born in Texas, but I watched too much British programming as a child, and my dad was from all over. So, I sound like a bizarre cartoon character. Some people like it, I used to have co workers call me up expressly to hear me talk, which would calm them down. Maybe it was just in contrast to the person they had on hold that was screaming at them, but a few people did this. That said, what I think of as “my accent” is disappearing. I’m ok with that, and I’m not sure everyone wields it in the same manner I do.
I dunno, people and language are weird, long before you even get into common phrases and accents. English is a weird crazy language that adopts from other languages easily, but truly changes slowly. I’d say it’s “anything goes, as long as you can get away with it”, If your go-to expression for that idea causes you to work hard to explain it, you’ll figure out another way of expressing it.