Have you ever tried to solo griefgank a Cutter or Corvette in a small fighter? It's not impossible, but the best chance of success requires teamwork in a wing. PvP is the epitome of co-operative gameplay. You watch almost endless mutual wing fights griefganks on YouTube for details.
There is no reluctance to lose access to players who don't actually exist. As we've seen, there are plenty of spaces in Mobius for anyone that wants them.... players who aren't willing to participate in PvP are already playing in PG or Solo. Adding a higher cap to the PG doesn't make it anymore enticing to people who dont want to be there.
Adding all the disparate PGs together, you get the same result as if you add any two small numbers together... sure it will be objectively larger, but it isn't going to be big enough for anyone to actually notice on a day to day basis; "at least one other commander every other session", becomes "one commander every session", or with this new found emergent co-operation being predicted, "a wing of 2 every other session".