Well, I did say a style of rock, and I would not categorize Prince or Graham Central Station as rock artists per se: Funkadelic is more soul and funk, no? Not to mention that certain bands are labeled differently now than they were back then or would be now. For example, the prog tag wasn't used till much later, and even some have a tough time calling a band like Pink Floyd progressive, since their sound and style was more rooted in psychedelic rock, but they were certainly a progressive band in the most literal sense of the word, so they almost always get the prog tag now, even if they were never called that back in the day.
Agree about Prince and GCS, more soul/funk, though Larry Graham (claimed his Grandmother taught him his signature slap bass technique) came from Sly Stone, an amalgam of pop/rock/soul/funk and purveyor of multi-culti sounds like Santana and War. Even further back, pianist Jelly Roll Martin certainly didn't INVENT jazz as he boasted, though he played an important role in some of the first jazz TRANSCRIPTIONS, and he noted the Spanish tinge about a century ago, Duke Ellington performed Caravan and Dizzy Gillespie incorporated Afro-Cuban rhythms.
My favorite Sly - Thank You (Falettinme Be Mice Elf Agin), Larry Graham's monstrously BUMPIN bass line, a circa late '69 single released on his '70 Greatest Hits album
https://www.youtube.com/watch?v=N5BP2KlPD4U
By the time of There's A Riot Goin' On (late '71), Graham had departed, Sly retreated behind a mountain of cocaine, blizzard of reverb and wah wah and largely his beat box overdubs, crafting his dark (and one of his last) masterpiece.
Africa Talks To You
https://www.youtube.com/watch?v=0R15zKDvYus
Thank You for Talkin' to Me Africa
https://www.youtube.com/watch?v=jXSM6f1epg8
Funkadelic did play soul/funk, but to me were more about the delic. The Parliament side of the P-Funk equation definitely represented the more soul/funk side of the equation, with more emphasis on the bass, the late visionary Bernie Worrell's ingenious synth arrangements as well as ex-James Brown band leaders Maceo Parker and Fred Wesley (a.k.a. The Horny Horns). My three favorite Funkadelic songs are Maggot Brain, Cosmic Slop and Red Hot Momma (love the Pedro Bell covers on the latter two replete with the possibly Sun Ra inspired Afronaut iconography), with a decidedly rock guitar emphasis. The late electric guitar wizard/pioneer Eddie Hazel displayed a virtual Hendrix-like mastery of feedback, and a few members of that band may have been acid casualties. Stax soul expert/authority Rob Bowman did a series of great liner notes for Funkadelic's albums, with the best being a lengthy essay (though you basically need a scanning electron microscope to read it!

) for the two CD singles compilation, Music For Your Mother.
https://www.youtube.com/watch?v=JOKn33-q4Ao
https://www.youtube.com/watch?v=H6SS7JDVRo0
https://www.youtube.com/watch?v=GeNkRuYHy8k
* As for Pink Floyd, I just never thought of them in the same category as obvious prog bands such as King Crimson, ELP, Genesis and Yes, but understand why they are categorized that way by many (Moody Blues and Hawkwind aren't always as obvious, either).