I seriously don't understand what people expect in these discussions, though. The situation is straightforward. A small but vocal minority of Signal's user base wants non-phone-number identification. Signal hasn't prioritized that feature. Put up, or use a different messenger. How is this complicated?
Don't pick horrible messengers, like ones where encryption isn't enabled by default, or doesn't even exist for group messages, or isn't built on a protocol anyone understands or has reviewed. But even with that constraint, you have options.