I think matching the same people repeatedly is making HG queues more dead.
Matching quickly with the same opponent = incentive to leave stamp/game.
Matching a bit longer with new opponent = incentive to stay.
Better to keep people waiting until a new opponent is found.
But I also understand that
waiting long queues = incentive to leave.
waiting short queues = incentive to stay.
So maybe a toggle - like the cross-region matchmaking thing - might help.
Anecdotally speaking, most of the time, I match with different ships (1-5 minutes queue time in EU) - until I keep matching the same stamp champ ship repeatedly - and then I leave game.
If this match repeat prevention mechanic was active, instead of matching the stamp champ again (in 1-5 minutes), we'd take longer to match at first (3-10 minutes queue time) - as we split queues of the new incoming ships with the stamp champ.
But with better retention (due to new matches each round), the new and old incoming ships get to match with not just the stamp champ, but also the 2nd-rate crew, 3rd-rate crew, etc.
Overall, this enlarges the pool of hg players remaining in the game, which might shorten queue times.