Multiple exits is a great way to protect people in the event of fire, but it's not the only one.

In the US and Canada where the 2 stairway rule is in use there has been a huge unintended downside of dictating the form of all low-ish and medium rise apartments for decades.

When you need 2 stairs the natural, efficient form is a wide building with a long central corridor with stairs at both ends. Building something that wide generally requires assembling multiple parcels of land and a long, drawn out planning process and large amount of capital investment. Small apartment buildings on a single parcel can't ever pencil out due to the space required to be dedicated to stairs.

Combine in the additional code requirement for bedrooms to have windows (for both quality of life and safety egress) and you get the vast majority of apartments having a limited number of bedrooms with windows only on one side of the living space. 3 and 4 bedroom units that could economically efficiently amortize the high per sq ft cost of kitchens and bathrooms waste an enormous amount of space, so they simply don't get built. Anyone who wants to raise a slightly larger family, live with multiple generations, or split costs with multiple roommates has no apartment options, they are forced to look at high cost, low density urban sprawl.

We currently have prescriptive requirements that dictate things like multiple stairs. We need to switch to outcome driven requirements that require fire suppression and safety over a given period based on occupancy and building size to give firefighters a big safety margin to respond. Then develop those outcomes into tested wall structures with a combination of fire suppression and prevention techniques that developers can adopt. Multiple stairwells might be part of the fire plan for a building, but it also can include things like sprinklers, concrete stairways, and automatic fire doors.