It really would have been more concise to just write "I don't care what you write, I'm right and screw everyone who disagrees."

You keep treating every single innovation as though it's assured that it will one day be adopted into the "standard" (as much as such a thing can be said to actually exist) language at some point in the future, and dismissing anyone who disagrees. I hate to be the bearer of bad news, but this is actually part of that natural evolution of language you hold so dear. If enough people see a novel form or word and reject it, for whatever reason, that innovation has hit a dead end and won't last. The sort of names you're championing might be enjoying rising popularity right now, but it's a mistake to assume that means all of them will inevitably become accepted. Some of them will, and many more will fade into obscurity.

These names are not immune to any criticism just because you've decided that anything goes and to say otherwise is bad linguistics. Names come and go all the time, some for some fairly rational reasons, some for entirely arbitrary ones. It's not hard to rationalize why Adolf has fallen off precipitously as a given name in the US, but what's the basis for Clarence going from one of the top 50 names for boys in the US to not even cracking the top 1000 for the last 45 years or so? The truth is, it could be anything. Sometimes people stop using a name because it's considered old fashioned, sometimes it's supplanted by a new variant that proves more popular, and other times it's just because tastes have changed and people find it ugly or embarrassing, rather than being the perfectly normal name it had once been.

I am, however, unaware of any case in which a name faced with losing its popularity or acceptability has been saved by someone riding high on their own self-righteousness telling anyone who dares criticize a name "You're all ignorant cretins, don't you know linguistic prescriptivism is not widely accepted amongst linguists?" while ignoring the fact that they themselves are trying to be prescriptive in their own way. Natural language is not, to the best of my knowledge, a teleological phenomenon. Just like evolution in living beings doesn't have any special design or end goal to be worked towards, there is no perfect form, no grand design that languages are all working towards that you can compare against to assess whether a given innovation will be accepted or rejected in the course of time.

Outside such obviously insane stuff like the child abuse masquerading as a name that Elon Musk inflicts upon his children, none of us can say with certainty whether a given name will stand the test of time or not. People choosing to adopt them or not, giving their opinions on them and popular sentiment is all part of how that will ultimately get determined, and you just want to come along and browbeat people for engaging in that and expressing their own views on names. How about you propose your own objective criteria for analyzing the viability of a given name going forward, oh wise one?

Okay, so, “-ly” is equally valid as an English place-name spelling varient of “leah”. Don’t believe me? Ask the English Place-Name Society:

And? Again, thank you for admitting that despite cranking out a fair bit of text, you don't seem to do so great on reading comprehension. Just to repeat it again, with emphasis for you.

You can make a case for something like Ashleigh, where -leigh is used as an alternate spelling of the -ley from Ashley in all sorts of English place names, with the same meaning or a similar one as -ley has in the name Ashley.

Huh, what do you know, the -ley/-leigh bit actually means something in the name Ashley, and it shares this meaning the -leigh used in place names. Yet Emily is derived from a patrician surname from ancient Rome adapted to better conform to the norms of English, or as a feminine form of the name Emil. In either case, the -ly in the name Emily is not cognate to the English -ley or -leigh. So instead of being one variant amongst many equivalent lingering forms that predate modern efforts to standardize English orthograpy, that -ly isn't even a discreet morpheme on its own, and the name would be better treated split into Emil and -y. But sure, tell me again how it's unconscionable to say that people deciding to jazz it up and be extra by turning it into Emmaleigh are the cool-headed, linguistically grounded voices of reason in this case.