Apart from having people play together but not same loot it feels like SP P8 tbf
I think you just either play SP or go Bnet precisely for two reasons :
Able to play with others
Able to trade
In your scenario you take off the trade option,
I think this would bring new good things but would a lot of people play it ? Doubt it
Yeah apparently quite a few people did the POE 2 online SSF thing which surprised me. Encouraging players to actually group play (not get 8 players in a game and solo content) is something id like to see, and this feels like an interesting way to do it.
I think group play would really be enhanced by the loot limitations of a no-trade environment....youd see a lot of improvising, using whats available, likely spinning up new characters based on a single drop etc.