I think in some cases, it can be helpful. I grew up in the 90s. I knew lesbian and gay, but that was about it. I didn't know bisexuality was a thing. When puberty hit, I was very confused and frustrated with myself for not being able to "figure out" my orientation. I could remember having a crush on a guy in my class, but also noticing how pretty some of the girls were as they walked down the hall. I thought that I could be attracted to girls or boys, not both. I thought that there was something wrong with me, like maybe I was gay and didn't want to admit it, or straight and didn't want to admit that, or that I was a mess who just couldn't make up my mind.
If I knew what bisexual was in high school, that would have helped. I don't think I would have wanted to "label" myself that at the time, but it would have been nice to know that something like that existed.
Labels can be used to hurt others as well...I think it comes down to how they are used.