And this is the crux of the argument. It's not that most Background features are a big deal, I think the only one I've ever heard complaints about was the Outlander basically destroying old school survival exploration.
It just comes down to how strongly you feel about verisimilitude. The background features are metagame elements, and 5e is pretty light on those, to the point that the few that do exist, get a lot of notice. More than that, they are metagame elements that the DM is urged to make work, and are invoked by the players, not the DM, who is, by actual definition in the DMG, the "Master of Worlds".
No, there's not much good reason to deny a Background Feature being used from a "it's a game" standpoint. But a lot of people, to varying degrees, are very attached to having a cohesive narrative. Upthread a ways back, I pointed out how these sort of coincidences of "just happening to know a guy" are a staple of the kinds of pulp stories that D&D was built on.
But not everyone wants to play that game. Maybe they want a grittier, closer to the ground experience. Thieves' World instead of Leiber or Tolkien. A metagame element that can be introduced at any time, where it would be completely unbelievable might take some people out of the story.
And immersion is important to a lot of people.
As has been noted, we make exceptions for spells generally because we accept (or have been trained to accept) the concept that magic can do amazing things that not-magic can't. The other day I watched Seraphim Falls for the first time, and I really enjoyed it, yet was surprised to find it was panned for it's few "maybe supernatural" elements. "What, did these people not see Pale Rider?"
But it just goes to show, D&D can be played in a lot of ways, and some of those ways have no room for "oh hey, guys, it's my cousin's sister's brother! He can help us!" That doesn't make them bad, it might make them not your preferred style, but it doesn't make them bad.
Like, Lanefan and his desire to make climbing out of ravine potentially an all day challenge that costs resources or a blip on the radar, depending on a single die roll? Not my cup of tea. I don't think my players would enjoy that. But, by all accounts, his players do.
And I can't say "well, that's not D&D" because D&D is a big tent. But Backgrounds, as presented, don't work with all the ways D&D can be played, and the books don't take that into account. Not once. They say "these are Backgrounds, DM, make 'em work".
Just as there are DM's who want there to be a chance for spells to fail when cast, or worse, have demons show up on occasion to tear the Wizard apart for daring to cast magic missile, there are going to be DM's who are going to look at a rules element like that and balk.
Upthread, I gave of examples of this very thing happening, and it can happen at a lot of tables, even tables run by DM's who would be on board with this sort of thing, but in the moment, have a knee jerk reaction of "this ruins my story" or "this seems too easy" or "where's that cool scene with my annoying bureaucrat?".
It's a proud nail. It sticks out because it appears to be saying "this is how D&D should be run" to some people. But D&D is for everyone, not just those of us who might be perfectly happy with giving players more agency in our games.
And it's changing. For better or for worse remains to be seen. And here's the thing- if you like the way it is, you can keep using it. Just as people who don't like it, don't.
I think by now everyone knows, you're not going to change the minds of those who don't like Background Features. I think that's a shame, because they can be great tools, but I also know that not every tool is needed for every job. I don't need a ball peen hammer (I hope) to fix a blue screen on my computer or unclog a drain. You probably shouldn't use a plunger to fix a brake line.
Of course, this post will get some likes, but I know others will ignore it and continue the debate, lol.
