My first thought is that it would be nice if we could just get more people to give citations in any format that would be great step.
As to different styles, I think it depends upon whether you are talking about the actual wording or the way the citations are presented.
a)The style or wording of the citation itself. The guide refers to both Chicago style and Evidence Explained which is an individuals interpretation on how to reference primary sources using Chicago. The problem for us outside of the US is that it is not a work easily available or I think used much.(Amazon UK does not stock it, you can get it from a Market place seller based in the US .There are no UK reviews. ) There are some online examples but few seem to cover the sources I am most likely to use.
I don't think there is a standard referencing style here. The University of Strathclyde produces a guide which is very helpful for the sources from the UK. The only journal that is vaguely genealogical (Family and Community history uses a 'British Chicago', other local history journals use MHRA.
Journala and genealogists in other countrie may also have adopted styles more appropriate to their needs. (Perhaps why wikipedia accepts varied styles) At the moment though, I haven't seen anyone 'policing' the wording of a citation, except perhaps when it is too vague.
b) The way the citations are presented.
The big problem is that if there are lots of idiosyncratic methods it will make editing of open profiles difficult.
One form of Chicago , and as far as l can see from the bits on the internet Evidence Explained uses numerical subscripts linked to foot or endnotes. ( i.e. what we place between <ref> </ref>.)I agree it takes time to learn and I hated it at first (was used to Word where you just hit insert footnote) but it works and I agree with the emphasis in using it (though the style guidelines also accept an astericked list)
In Chicago ( and EE?) and also several other referencing styles, a first full citation is given but later citations are in shortened form. This is followed by a sources list or bibliography.
Not many people on wikitree use inline citations followed by a source list. I think it is probably 'over the top' to include a sources list in addition for many short profiles . It also produce a problem if the bio is reordered and the first citation becomes a subsequent one.
One member (one who takes great care over his research and sourcing ) just uses the shortened form in the footnotes with a full version in a source list. I think this works very well and is easy to follow but it now produces an 'error' (repeated citations or almost empty tag).
We now seem to be being directed to the method referred to as 'advanced sourcing' https://www.wikitree.com/wiki/Help:Sources rather than accepting the simpler (in terms of formatting) style as recommended earlier. Personally, I think this adds a barrier to those who find the 'coding' element difficult.I avoid working on these profiles. (I'll admit, I hate the way profiles 'read' using this method and feel it is quite disimilar to elsewhere)