It's possible for a gold 1v1 player to get carried into master league in team games, even 2v2. I know because I've done it myself with some friends that are gold. However, this generally happens after placement matches and not through promotions. In the first example linked of the gold 1v1 player, his partner is a top 50 grandmaster. His MMR is so high that even going 3-2 will place them in a master league team. In the second example, I believe the player is either portrait farming or intentionally losing to play easy games in bronze 1v1 league, but more likely is portrait farming.
As far as team vs 1v1, this is an old topic, but I'd like to put in my 2c. Team games aren't near anywhere as competitive as 1v1s. I just started playing 2v2 with my partner and we're already playing top 100-200 teams. That would never happen in 1v1. Our builds aren't fleshed out and we still lose to a lot of "dumb" things sometimes. The reason that team players get a lot of "hate" is because people imagine high ranked team players to be prideful without having correspondingly deserving skill.
Team skill has overlap with 1v1, but there's definitely some skills more emphasized in team games than 1v1 and some skills more emphasized in 1v1 than team games. However, 1v1 players generally have better mechanics and multitasking, which is more in tune with what people consider to be "skill." However large that difference is, it would be very hard for me to believe that two true (mmr stable) 1v1 gold players can consistently perform at a master league level in 2v2.
