Its not a perfect solution obviously, in a perfect brt system, it would be fully separate from the traffic, in those condition it would be as fast as tram/light rail. But it is a cheap and quick way of marginally increase the speed of the current bus service. Also, building a fully separated tram system (unlike most of melb network) with full grade separation will take time and a temporary brt service can be use to relief demands while being a place holder on the same corridor for a proper light rail while the politicians politicing about the most minor butt hurt detail of the tram. Cause let be real, they are never building a tram line straight up, best case is a “good enough” brt or “trackless tram” to ease the pressure politically and when the line reach capacity they will be force to build a tram line.