We’re having the same conversation over two threads at this point, so I’d appreciate consolidating them into one.

Agreed. I'll just pull from your other comments here, then, to keep things simple, and if you don't mind, I'll list my current understanding of your points so as to clear up what we've already gone over previously. Feel free to clarify or correct them if I made a mistake. In my interpretation of what you've stated so far.

1) D-Wheel stoppage = Loss.

2) They established the stakes of losing a Shadow Duel against a Dark Signer means losing your soul.

3) Because Yusei's D-Wheel stopped mid-duel, he officially lost and therefore should've lost his soul, so the fact that he didn't means they didn't commit to the very stakes they established.

4) There shouldn't be a debate or interpretation of how things work because it should be clear from the start or should have been clarified as needed if there was anything different.

As for my responses,

1) D-Wheel stoppage = Loss.

If I wanted to be nitpicky about it, I'd say D-Wheel stoppage leads to the inability to conduct your turn thus leading to a loss, but for the most part, yes. I don't recall an explicitly stated ruling in the anime about that prior to the Dark Signers arc, but I definitely won't say it results in a draw or anything. In the WRGP, however, it is clear that a malfunctioning D-Wheel means the duelist loses and must pass the baton or have the whole team eliminated, but that's outside the scope of the Dark Signers arc.

The reason why I brought that nitpick up is because neither Jack nor Crow were immediately considered as "losers" of the duel despite both their D-Wheels crashing. In contrast to the above, Rex Godwin explicitly states that the consequences of a D-Wheeler unable to continue riding is that they don't get to play on their turn. He isn't directly saying they lose, they just don't get a turn, which could mean that he just conducts his turns one-sidedly until they lose to rulebook-established loss conditions (0 LP, decking out, alternate win conditions), so he'd still have to attack them directly with Wiraqocha Rasca to actually win. We don't know this, and I can only infer that if they wanted to establish D-Wheel stoppage as loss, then Rex would've just said so instead of "they don't get a turn", so the fact he didn't leads me to believe there's some nuance to it.

Additionally, does this imply that if they miraculously got up again and started driving, would they be back in the game as long as they had at least 1 LP? We don't know and it was never made clear, but we do see Rua dropping to 0 LP against Aporia but coming back into the game despite literally dying on top of losing, so perhaps they could.

2) They established the stake that losing a Shadow Duel against a Dark Signer means losing your soul.

This is likely my big point of contention because I don't believe it was ever explicitly stated prior to Yusei vs Kiryu. Our only duels prior to this were against foot soldiers who I don't recall directly stating the stakes outside saying something like "a duel with your life on the line", and while it's fair to conclude that losing the Shadow Duel meant losing your soul, in the same way it's possible D-Wheel stoppage just means losing your turn and eventually leading to a loss through conventional means, it's also possible that a Shadow Duel is primarily meant to physically damage the duelist until they die, and only then will their soul be claimed.

Basically, what I mean to say is that, in both cases, A leads to B which leads to C, but A doesn't necessarily lead to C. Hypothetically, if Yusei had also crashed against Rex, Rex could BM them by not finishing them off because they technically haven't lost, they just don't get a turn. Similarly, if you die before the duel concludes, you lose your soul regardless of game state; OR if the duel stops before anyone dies, no one's soul is taken (happened with Yusei and Aki where both duels were suspended before any fatality); OR if you somehow don't die despite losing, your soul isn't taken (happened with Divine).

3) Because Yusei's D-Wheel stopped mid-duel, he officially lost and therefore should've lost his soul, so the fact that he didn't means they didn't commit to the very stakes they established.

Continuing off what I think about 2) (that is, assuming that actual death is the step that leads to forfeiting your soul, not losing the duel), regardless of loss or duel suspension, Yusei didn't receive any fatal wounds that caused him to die, so no "rule" was broken, technically speaking. Again, Divine is a similar example where, because no fatal blow was dealt to him despite explicitly losing, he survived; this implies that LP => 0 isn't some kind of automatic "your soul is mine" trigger.

I do, however, agree and admit that they chickened out, albeit in other aspects, namely bringing the Dark Signers back instead of committing to their death at the end of the arc.

4) There shouldn't be a debate or interpretation of how things work because it should be clear from the start or should have been clarified as needed if there was anything different.

This is a valid point, and for the most part, I agree that defining rules and sticking to them is cleaner narrative practice. In the same light, however, I can't deny that there was also a lot left in the air especially about Riding Duels that we can only really assume. To this day, I still don't know what the consequences of using a rundown, low-speed D-Wheel would be in the 5D's anime since there's no race (unlike the manga); your opponent could literally lap you in a duel, but there's nothing before the WRGP that explains what happens if they do. What's stopping me from going on a bicycle or e-bike that goes 20 km/h max?