You could argue a four man team in Update 5 would complete the mission four times as quickly, influencing the BGS four times as much, so there's that incentive. I think there IS a difference between "sharing missions" and "team missions" more like Horizons but (1) they need uppicking from each other and (2) I'm not sure.
I suggest, start a seperate suggestions / discussion thread on it.
There are already many threads concerning OD and bgs i started 1 in the past 2, they dont read them anyway, or they wouldnt have made these adjustments.
The thing is, a 4 man team doesnt give a 4 time benefit in time needed to complete the missions. quite the contrary i believe.
-transport / restores / salvages all are unaffected by having more players there to do the work
-anything covert or no-kill or anything where you dont want to kill out the entire base. is not helped by more players, stolen profiles to get in somewhere are individual, so no help from more ppl there.
-Sabotages / Shutdowns / Infiltrations / assasinations only if you can do them loud and heavy with the pospect of killing the entire base.
-massacres and clearing scavengers would be helped by more ppl yes.
But even if more ppl would be helpfull: a mission consists of flying there do the objective and flying back. seeing as only the hard and loud are helped by more ppl, and those are generaly the fastest to do, Time needed is not really helped
So, again, no, this just gimps the meaning of ground gameplay in relation to BGS even more. while it was already very low