is very much team dependent
Maybe not "very much." It's easy to over-state it. I'd like to see an in-depth analysis on this, but I suspect (a) your usual position in the batting order and (b) your slugging have more to do with it.
Here's what I'm building that hypothesis on. Let's look at some 3-spot hitters last year.
Mike Trout hit third in the bulk of his games, and occasionally second. He had 171 PAs with runners in scoring position, on a perfectly mediocre offensive club with good but not phenomenal batters in front of him (OBPs around .350).
Now let's look at the top of the league.
Xander Bogaerts was usually hitting third—sometimes second—on an offensive juggernaut. Even with a better top of the order (OBPs around .375) and a deeper lineup, he had scarcely more PAs with RISP than Trout did: 184. At his or Trout's rates, that's maybe a difference of 4 to 6 RBIs. In reality, Trout had a much better SLG with RISP (.592 to .423), and got more RBIs out of those PAs (72 to 65, and 100 to 89 overall).
Next, Kris Bryant. He bats second a little more than third, but he's worth looking at. He's on another powerful team at the plate, though the top of the order is not necessarily better than Trout had, and of course you have the pitcher or bench player in the 9-spot to think about now. Dexter Fowler played most of the season at lead-off, with a .393 OBP, but other Cubs who took on that role were closer to .300. Bryant gets 164 PAs with RISP. It's a lower figure than Trout's, but by a very small amount over a 162-game season. Expect a couple less RBIs, certainly—but actually he did quite a lot less with RISP than Trout, hitting .263 with a .474 slugging and only knocking in 53. It is a testament to his power that he actually beat Trout out on RBIs. He did a lot more with a runner on first or no one on that Trout did last year. If I'm a Cubs fan, I'm feeling good about that one.
Now to the bottom of the league.
Philadelphia had a poor offense last year, but one of their batters, Maikel Franco, actually came up to the plate with RISP every bit as much as the three hitters above. In 179 PAs, he knocked in 71 runners. It is a testament to his relative lack of power (at 23) that he finished 14 RBIs short of Kris Bryant in the NL table: unlike Bryant, he wasn't able to knock in many runs "from a stand-still," so to speak.
Freddie Freeman on the Braves had 167 chances at the plate with RISP, meaning that the Braves were no handicap to his chances. Despite only 53 RBIs from those PAs, he finished above Franco and Bogaerts in RBI totals because, again, he was more of a force on his own. Better power, more useful with no one on or a runner on first.
Look around the league, and you'll find the same kinds of numbers for guys hitting around second, third, and clean-up. The difference in opportunities these players have is greatly exaggerated.
I wouldn't want to compare someone hitting third and someone hitting sixth, even if they were on the same team. But cross-team comparisons are fair, I think.
I wouldn't use it as a predictor of future performance, or a gauge of a player's value the way you might when looking at adjusted stats and so on. But the scorn for RBIs is, I think, far and away overdone. RBIs do indeed reflect a player's real, day-to-day contributions to their team. Like goals in hockey, you may get the occasional easy set-up from a good teammate, and we shouldn't make much of small margins (like 5-8 RBIs on the year), but it ultimately is on you to knock the runners in. And, frankly, there isn't a wide spread in chances to do so, provided you're playing every day and you get a good spot in the order.