The argument is that if only a handful of neighbourhoods absorb new density, those areas carry all the growing pains, congestion, construction and changing streetscapes, while the rest of the city keeps its rules unchanged, which supporters see as unfair to the neighbourhoods doing the absorbing.
Applying the change city-wide, as Saskatoon did through its zoning bylaw amendment, spreads that adjustment more evenly: every established neighbourhood gained the same as-of-right options rather than a select few being singled out for higher density while others stayed exactly as they were.
Whether that has actually changed what gets built near you, and what it does to your lot's value against the city's $444,700, is worth asking about your own street rather than the citywide policy debate. Get your hand-reviewed valuation from Joel Dyck.