Why is the Ballroom style under the Electronic genre?

Style: Ballroom
is only available when the Electronic genre is selected.

Was this intentional?

Yes, it's meant to be ballroom as in MikeQ building a whole career out of that Eddie Murphy via MAW sample aka the Ha Dance death drop.
zin provided a definition when requesting the tag, it got lost in translation.

https://www.discogs.com/forum/thread/368197?page=4#7074957

Ah, OK, thanks.

Mais non!

https://www.youtube.com/watch?v=5zUiy2CnVnE

Mais si !
https://www.youtube.com/watch?v=oCERfa8LcS4

_jules
Mais si !
https://www.youtube.com/watch?v=oCERfa8LcS4

Wow, really? It doesn't take much to make a Style.

Jarren
It doesn't take much to make a Style.

Apparently.

What about the newly added 'Twist' style?
Far as I remember, it was a dance and not any particular style of music.

I'm not disputing hundreds of songs added the word 'twist' to their titles but it's debatable if this actually constitutes any actual definable style.

And yet oddly enough 'Western' as in Country & Western still goes ignored.

Several Latin styles are the names of dances.

I've seen releases described as e.g. "French Twist records"—James Award, Teddy Rush Et Son Orchestre, Star Twisters, etc.—although yeah it's pretty niche, hard to say if it's really a genre per se.

Maybe check the thread where it was probably requested https://www.discogs.com/forum/thread/771553