I think the USN is a bit spoiled for choice as they were able to build an amphibious fleet of only larger ships like LHDs, LPDs and LSDs over the past half century, meaning they were able to form ARGs around those vessels primarily. I imagine if the Chinese Navy had a large fleet of those sort of ships they would probably form ARGs around them as well and leave LSTs for other roles.
However, given the Chinese Navy won't have that large of an LHD, LPD and LSD fleet (relative to the USN!) in the foreseeable future (let's say early 2020s), I think it may be sensible to consider LSTs as a potential component in whatever their ARG equivalent of the foreseeable future may look like.
And that I think leads us to the question of what capabilities a Chinese Navy ARG will seek to have, what kind of endurance, presence, persistence should it have, and how often the Chinese Navy wants to have an ARG actually "ready" and out at sea.
I personally can't see the Chinese Navy of the near future seeking to field an ARG in as permanent a way as the USN does or having them out at sea as often as the USN does, however I do think LHDs, LPDs and LSTs will often train and operate together for certain types of amphibious assault contingencies and may occasionally deploy together as sort of a pseudo USN style ARG for temporary periods in certain regions either as part of training or due to an actual contingency, but then after that's done they'll return back to their own units.
The greatest "limitation" of an LST, IMO, for being part of any sort of permanent ARG that is deployed in the USN fashion, is its relatively smaller size and its accompanying small endurance, compared to say an LHD or LPD.
Of course the PLAN's make-up and definition and use of a PLAN ARG is going to vary from what the US policy and goals are.
But it does not mean that the PLAN is not thinking in terms of using LPDs and LSTs together to form Amphibious groups.
I honestly believe that for the PLAN, two of their San Antonio Sixed LPDs, couplded with four of their larger LSTs, and with the escorts to go with it, would form an effective amphibious landing group for their purposes.
And they will be able to put three of those types of groups together...or make the group larger if necessary to achieve their goals.
They are already doing exercises with Type 071s, Type 072As (or IIIs), escroted by Type 054As and various types od DDGs...including more recently adding Type 056s to the mix in the South China Sea.
And since it is pretty clear to me that at some point they are going to bu7ild 2-4 LHA tye vessels, it akes the case evn strnger.
But for right now, they are already exercising with multiple LPDs and on occassion have added several LSTs to that mix...or whatever you care to call the Type 072A or Type 072III, of which they have about 25 of those right their, plus another 10 or so older model Type 072s still in commission.
In the 2020s when they add LHAs to their Amphibiuos mix, they will have even more capability...but we will worry about that when the time comes.
Right now, they are exercising fairly regularly with those other vessels, and there are very few Navies who coul field what they can field (in terms of over all numbers, both in terms of the individual grous, and in terms of the total number of groups), like they are doing.