How do i send bcc texts on IOS 17.0.3?

Yes, you are right 👍

The option to disable "group messaging" is gone.

Before uodate to iOS 17:

After update to iOS 17:

All you can do is -> send feedback to Apple, see -> Product Feedback - Apple

That has been possible before (I thought), see -> Name a group text message on your iPhone, iPad, or iPod touch -> Name a group text message on your iPhone, iPad, or iPod touch - Apple Support

Or do you mean something else?

In the past, it was only possible if everyone in the group was using iMessage. And, in fact, that article you linked to still says that:

Remember, you can name group iMessages, but not SMS/MMS group messages. To name a group text message, everyone needs to be using an iPhone, iPad, or iPod touch.

But, I tested it (after someone somewhere else on the forums mentioned it) and was able to name a mixed group.

Has it ever been possible with the 'older' iOS version?

Another interesting change is that you can now name group message threads that include SMS users. I wonder if these facts are somehow related.