I think there are levels of depth to which you would express affection to a romantic partner in any love language, that is beyond what you'd do for a random acquaintance or a friend or "anyone".

There are almost certainly topics you wouldn't talk about to anyone except your partner. Your deepest secrets. Your most vulnerable emotions.

There are "nice things" that inconvenience you, that you would do for your partner, and not for Joe Blow down the street or for your friends.

You might hug your friend, but would you massage their feet after a long day? Really? That's an example of physical touch that isn't sexual, but many would reserve for their partner. Same with extended snuggling, holding hands etc. That's all stuff I would do with my husband but not with my platonic friends. And yeah, sex is a form of physical affection that is usually saved for one's partner. For many people, the extent to which one is physical with their partner is much greater than for their platonic relationships, and that is often what differentiates a platonic and a romantic relationship between most people.

Quality time as well, you can spend quality time with anyone yes, but I'd expect you to spend more quality time with the person that you claim to love more than anyone in the world. You'd likely sacrifice quality time with lesser bonded people to spend time with your partner, if you had to choose.

And for gifts - you'd likely be prepared to spend more time and effort picking out a gift for your partner, than for anyone else, if that was your love language.

So yeah, they are all equivalent and valid, and they all have levels to which you can express affection to less bonded relationships and levels to which you'd likely only go for your romantic partner.