Mostly due to backward compatibility, as there were a fair amount of Windows applications that loaded DLLs to add a custom panel to Control Panel.
Well, many people on HN hate that Apple has a poor record on managing backward compatibility (like deprecating 32-bit apps or Carbon), but if they do to the scale of Microsoft, this is what happens.
I wanted to associate a file type with a program in Windows 10 recently, and I found at least 4 different menu items that lead to the same unhelpful modern screen. Unhelpful because it only let me pick 'App Store' Apps, not anything else I have installed. Some answers online suggested these very item as ways to go to the old screen but it looks like they closed that escape hatch.
I was having trouble because it was a 'special' file type (CMD) so the context menu didn't offer the Open With option, I suppose to save this clueless user from himself. So instead I dove into the registry and did a manual hack which will hopefully stick around between updates.
with something with less functionality and even less logic on where to look for a particular setting?
Windows is so poorly designed that I still wonder why there's Settings as well as Control Panel offering mostly the same settings, and old settings dialogs from Windows XP or Windows 2000 are still around!