So I think it would be beneficial to everyone to add a Mercy medal(?) so players don't just have to sit there getting killed over and over again during obj matches.

Example to what I mean is this last match I played with my Fiancee (She has only played Halo for maybe 6ish hours off the top of my head) we got Oddball on Snowbound against a couple of sweats who had the ball till it got to 144 and then just proceeded to spawn kill and the such, Just a 2v2 social match so I wasn't really trying all to hard since i'm just playing with my Fiancee for fun. Just seems pointless to have to wait 8 minutes for a match to end because the other team doesn't want to just hold the ball for 6 seconds. I get these are older games but it just seems so boring for both parties to have just waste time.
The ultimate reason, and this community won't admit to it because then they'd have to acknowledge the progression system is seriously flawed, is that teams like the one you face look for every opportunity to ensure they reach their XP cap. Rather than just winning outright and getting maybe 75% of the cap, especially on an H3 map, they proceed to spawn kill and drag the game out because they want to make sure they get their points. Not saying that sort of thing wouldn't happen prior to the progression implementation, but I've noticed objective games turning into team Deathmatch more and more because people are looking for any chance they can to pad their xp.

As for the mercy medal, I agree with you. If by a certain point, one team is just trashing the other, there should be a mercy call. It helps out a lot in Destiny.
That is why it's best to never select objective in the composer and only play Slayer since the majority of the objective games just turn into slayer.
My experience in team arena a year or more back was that a lot of teams used objective as a way to boost their kd stats. I personally don't enjoy camping a far inferior team for 10-15 min, but evidently some people do...
Sounds like you just got some toxic players. Sorry to hear, chief. It pisses me off when people pull this stuff.
It seems that you just encountered some bad eggs in a very large egg basket. Every objective match I have played, everyone went for the objective and it only turned into a slayer match when someone had said objective.