Nah, it's way more than that. When I watched these clips on Youtube at first before I saw the show, it's really really easy to think they're actually in a relationship. This isn't like some of the other shows where fans are just being delusional and they think two attractive character together = they must be a couple, there a ton of situations that just straight up sound like they would be a couple if you go in blind. I have a hard time believing anyone would think there isn't something going on if one of them was the opposite gender or if this was on a gay-themed show.
Christmas scene aside, you've got the fact that Eddie's kid basically treats Buck like a second dad, Buck and Eddie have keys to each other's place, and they have an argument in the grocery store over Evan not being able to see Buck. That one scene with the girls hitting on Eddie fairly early on and him saying they weren't his type and Buck agreeing. More nudge*nudge moments from the directors with that webcam scene with those viewers saying they should date. They spend most of their time together, even when they were both in relationships. Like, you could probably pull up a random M/M fanfic and find these same exact things with nothing changed except they kiss or something and it would be a romance.
And it's not like the writers are oblivious to how that comes across, that's why they keep poking at it. It's not even in the same way that says Scrubs or House has their super close male male friendships where they act super gay for each other but it's clearly for humor and while, yes, some people still ship them, most people see it as just a sign of their friendship. Buck and Eddie just come across as two people in a genuine relationship in everything but name. Intentionally.
