@Flick (disclaimer: didn't read the article because the original was behind a paywall and archive.ph doesn't work for me anymore, so going by the quoted bit)
Warning: research/hypothesis geekery ahead
Students of linguistics, since elderspeak was first identified in 1981, generally regard it as a linguistic power play...
Ok, this has become one of my peeves of late.
So much in sociolinguistics is explained by the catch-all idea of "power", and when that happens, alternative explanations are rarely suggested.
Just off the top of my head, I could suggest an alternative hypothesis of nurturing impulses. The variety appears to be similar to way adults speak to small children, so might not the presence of an old person, quite possibly of some frailty, trigger similar nurture-coded language? Perhaps purely by mental association to nurturing behaviours towards children?
Mind you, I'm not saying this is the case, obviously. Just pointing out that alternative hypothesis are perfectly possible. And it irks me that they so often aren't explored, when "power play" is an easily available one.
The power explanation also doesn't explain why elderly people in specific would be the targets. Presumably medical professionals would have reason to attempt power plays on patients of all ages, if they think it helps them to gain compliance. Why not try that on a recalcitrant middle-aged woman, who isn't in the mood for taking her meds?
On that note, how much is the prevalence of elderspeak affected by medical professionald dealing proportionately more with old people, especially in institutions? Has that been taken into account?