I think its economics. I love my spring /pawl reels. However in todays market place, there seems to be only two economic options for these type of reels.
Inexpensive - re: phlueger
ReelExpensive Hardy and many mom and pop machinist type boutiques reel makers.
It seems as you said, Everything in between has some sort of drag. The bottom line, it is very expensive to engineer and manufacture high quality spring pawls vs. a lite weight drag reel.
The larger your quarry the more dependant, modern anglers have become on drag systems because they have never had the pleasure of fishing with a high quality spring pawl that can take the type of beating that a large Atlantic Salmon would put on this type of reel, nor have I.
My spring pawl experience ends at a 5 wt reel and 20 inch range trout, and I have fought fish on both s/p and drag and there is no comparison.
I hope to aquire a quality s/p larger reel next time I am lucky enough to be fishing for large fresh water quarry.
One other thing. I believe with the continued popularity of Salt Water fishing, that is why there are more larger Drag system reels. I have no dout that a well made s/p reel could handle the larger game, but not sure if it could withstand the inevitable corosion that come with even the best protected and cleaned gear.
A $ 2000.00 s/p 9 - 12 wt reel would be a blast on a small tuna or bill fish.
But it might break your heart as the insides rotted away!
ralph