Your argument seems to be mostly that "I have already done this way, therefore this way is better", which is a valid argument, but not very convincing to anyone else who hasn't implemented it. You act as if doing it with HSL was very hard when in fact it is a change you can do in like 1 minute.
I wasn't talking about indistinguishable colors, I was talking about many of the colors being actually just black, and your example seems to corroborate that. Of course I don't have the counter-example of how your gradient would look like if it was done using the HSL scheme, so I can't even say if it would really be better, I just tend to think it would, but I won't push any further.
In any case, please open a NIP proposal with your scheme if you care about standardizing this.