Very probably. Joël was a legend - almost as much so as Stefan. Although I wouldn't be surprised if it was "invented" by a number of people independently, and Joël was just one of them. I suspect Stefan Pochmann knew it was potentially a practical method as well, as did several other people.
Right after 3-style actually caught on, there was some talk about the possibility of using 5-cycles instead of 3-cycles. Wouldn't it be interesting if someday 5-style actually became a thing?

To make that possible, the big challenge would be to get where you can "see" how 5-cycle algorithms work, much as people currently "see" 3-cycles in their head now. I wonder if it's possible to do that generically?
Sorry about this essay in advance.
I've been thinking about 5-cycle corners recently, just as a fun thing to do. And i don't have a clue... It's well beyond my mental ability. But here's what i made and wrote down after a few hours of trying to work out what i believe would be one of the more simpler cases.
I wrote this when looking at this case (UBL - UFL - FRD - LDF - BLD) and it seems to work for all cases where 1-2 are in the U layer and the last 3 on the D layer in a particular orientation.
[(R U' R' L' U' L) D]
Pieces 1 and 2 (In order of the Comm direction, in this case UFL and FDR)
get solved together in minimal moves (Stay in accordance with general
Commutator rules). 1 of the first two pieces are moved aside, not to be used until the final moves, whilst the other is used around the "LOOP"... A sort of traveling buffer piece. In
this case piece 1 is used to swap out piece 4 so it may be placed into the
position of piece 5 then placing piece 5 into the buffer position... If
all done correctly, the loop piece will move on to interact with the
pieces swapped out in the first few moves, when reversing the moves, to finish it's journey as a traveling buffer having no where else to go but back to where it began
traveling. all whilst still following comm rules, i think... maybe, i don't know. That's the best i can
explain that...
R U' R' ( L' U' L D L' U L R U R') D'
\ 1 / -- \ 2 / \3/ \ 4 / - \ 5 / \6/
1. F2P (First 2 pieces)
2. Start of the Loop & start of main Comm
3. Interchange
4. End of main comm & mid point of the loop
5. End of loop, solving all remaining pieces relative to each other
6. Undo Interchange
() = the "loop" thing/traveling buffer
This only saves 2 moves over the two 3 cycles i would normally use and it's terrible in terms of speed, Here's another example that operates on the same principle but saves 4 moves over my normal two 3 cycles and is actually quite a bit faster IMO.
UBL - FLU - RDF - FDL - LDB
[D' (L' U' L2 U L')]
Sorry about the way i write comms, and also i think iv'e taken this as far as i can. A smart, experienced person should have a better look at this, they'd be cool to see. I have a few other's of this type... But that's as far as i can generate with intuition.
Any further input is welcomed.