Unfortunate choice of word.
Daiwa developed their Mag-Force nonlinear mag brake a decade ago, and continue to improve on brake rotors and annular magnets through current SV.
Shimano put their cookies in the variable centrifugal brake basket in the same decade, and their mag brake is an intention to not infringe on Daiwa patents.
Even on Daiwa with fixed or SV brake rotor spools (nonlinear mag brake), you set mag brake for the lightest thing you're going to throw, and you're done.
Only even-lighter lures could need more linear mag at mid-cast.
The seemingly mass-less spool is the key to casting light lures.
Light lures don't give enough jerk to need centrifugal brake at start-up. But if the spool is massive, then the jerk and inertia is from the spool itself.
The same holds true for the Daiwa moving SV rotor - SV doesn't move with light lures, giving you an effective light linear mag brake.
The low inertia of a low-mass spool gets all the brake it needs from very low braking loads, so more of your cast goes into casting, and doesn't need to be subtracted by the brake load.
In the case of old Ambassadeurs, the LW is driven from spool energy during casting, and even drives the spool from start-up jerk, so attention to reducing LW inertia is important.
The Roro-X spool gives up the added mass of the moving SV rotor complication, instead, using a lighter and even thinner-metal fixed brake rotor.
This will cast 3g to almost 50 yards on an 8' rod - the empty spool weighs under 5 g, and not much more when loaded with fine X-braid.
You also gain greater line speed and distance with the 34-mm-dia. spool, compared to the smaller-diameter spool on a packaged BFS reel.
I've fished this in the very same tide pass with 8' light game spinning, and this baitcaster will out-distance comparable spinning tackle.
This isn't the purpose of the little Ambassadeur - it's to fish light lures in close on a short rod, but you still tune to get the most from it.
The stock 1500C spool won't cast without centrifugal brake. You'll note I'm only using 2 fixed magnets with the shallow Avail spool.
Three grams is the lightest I'll cast with it, and 7 g is the most - nothing about this reel will ever need adjusting again - I did all my adjusting up front. Here's where I did the same thing with an Ambassadeur 4600C
to cast 3 g to 15 g.
The most impressive linear-mag-only-brake reel is ZPI Alcance.
Magnesium spool with titanium spindle and tuned mag-brake cam.
The speed and distance of this bench-tuned Revo compares to the aftermarket BFS spools I showed above.