Having been involved in the medal trade, including mounting medals, since the late 1970s I have observed the slow creep from swing mounted to court mounted over the years, until the latter method is now very much the norm. The original reason for court mounting was to prevent contact damage to the medals when they had to be worn frequently, particularly by mounted troops, or in the case of very long groups where much overlapping was required. There seems little point in court mounting two medals, then, other than for reasons of fashion.
Personally I much prefer swing mounting, and in particular I dislike seeing old groups, from WW2 or earlier say, being remounted court style by collectors or descendants of the recipients. Still, as I say, that's just my opinion.