The Old Siri Voices

Okay, I only have an iPhone and therefore have no idea on MacOS. So we once had these old compact Siri voices with their premium variants available for download. The first iOS version to have included them must be 8 or 9; don't really remember for sure. And then they were replaced with larger, more realistic but less responsive counterparts, which in turn, as far as I know, have recently been replaced with much smaller AI-powered versions. But I can still find those old compact voices like Aaron and Martin on my iPhone, and even have them speak by finding them in third-party TTS apps that list all the voices installed on the device. So why can't we use them with VoiceOver? I'd love to be able to use Aaron as it pronounces things correctly most of the time, and its intonation is also good. It's also quite responsive. Besides, you don't have to download anything additional. These voices are still part of the operating system but we can't use them in any way for whatever reason unknown to me. Why can we no longer use those voices if they're still included? I've already submitted my suggestion to be able to use the old Siri voices to Apple, but unsurprisingly, got no response so far.