But individual equipments could help to improve the survival rate of the soldiers... which is a big deal (to that soldier in question, at least).
However I agreed that you do not need top notch equipment and weapons to train the soldiers and it is certainly kind of wasteful to provide every single troop with very advance and good equipment when most would not see any actions throughout their service life or even be deployed in very hostile environment.
Anyway, China had a huge stock of 7.62mm rounds, Type 81 rifles and older infantry equipments that are still effective in today's standard, so really no need to change these for second line soldiers.
I'm not saying that the older equipment is useless or not useful for training raw recruits. I'm just thinking all military equipment has a certain shelf life for example the spring and barrels of small arms. These parts need to be replaced after significant usage.
I'm not advocating that there should be whole sale replacement of equipment. But a phasing out of equipment by attrition like, not making anymore parts for the type 69 tanks that are not shared by the newer tanks in the PLA tank fleet. They should just start creating bone yards for the type 69's to be cannibalized for parts for units still operating them until they are final withdrawn from service. Because it's going to be kind silly if they keep the 69 in front line service for another 20 or more years.
It also seems to me this could lead to a logistical headache in the future as well as a diversion of funds that could be used for modernization. This is almost like the same problem the Chinese military had during the first half of the 20th century.
It's going to be a rough day for those soldiers using weapons that fire 5.8mm rounds and accidentally receive 7.62 ammunition.
Unless the PLA is comfortable with having combat deploy-able units operating with significantly different equipment that cannot be supported by the same supply chain.