To the point of trying it keep it fun for them or limiting myself because they're not as good yet, I think that responsibly lies with them.
Back in the day Grim68 and I played Silver for months longer than necessary before jumping up to Gold because we didn't want to be leeches or bring the team down. I respected my teammates enough to want to pull my own weight. Sure we still failed from time to time, but they weren't compete embarrassments.
Yeah, I played Silver for way too long before finally moving to learn Gold. Something like at the 400 hour mark. Well into the point where I only needed URs.
But that's not the point. The point is these guys moving to Gold too soon make things more fun for us Veterans. Just takes one Veteran to make sure things go smoother in these poor pug lobbies. Plus playing with a weaker setups to better match the pugs, and now all of a sudden the game is more interesting. Stuff like enemy pressure pushing you back all of a sudden have meaning again too. Ditto for bosses being armour sponges again like they're supposed to be.
It's just like adjusting the difficulty level within one particular difficulty setting like Gold or Platinum. It's only normal to get the hang of all difficulty settings, with the final difficulty setting being handicapping yourself. Folks do it all the time, just check out YouTube and other gaming forums. Ever heard of the terms 1cc or no miss? These are folks creating extra challenges for themselves to keep continuing playing their fave game.