Gnome hates hacky solutions, they're implementing it now because it's finally well-supported in portals and in the freedesktop standard (btw, accent colours being a cross-desktop standard is something they avidly pushed for).

They also had a lot of discussion about how choosing some accent colours (particularly red) could have a detrimental effect on PC usage in terms of differentiating between dangerous or "destructive" buttons and other ones in dialogue boxes.

I.e. if red is your accent colour, then all of a sudden the red button that says "Yes" in an "Are you sure you want to delete this?" loses some clarity of being a dangerous/destructive action, because you're now used to seeing red all over your system. This, from a usability perspective, is bad.

They had multiple pages going over this, and other things, in excruciating detail, citing multiple UX usability studies.

I don't know if they came up with a solution to that or not, it's just nice that the team takes everything into consideration and thoroughly examines it.

I'm extremely glad Gnome thinks about these things and takes time to implement things in the best way that they can, rather than just rushing everything out. Attention to detail like that is a big part of why I love using Gnome.