It really wasn't so much the brakes, but the tire technology really needed to catch up. Even though Radials were around in the 60's, I don't think a lot of people could justify the extra expense. Drum brakes, especially the larger ones seen on Chryslers and Lincolns and Cadillacs are HUGE. Chrysler had some 11" x 3" drum brakes optional and when you consider the surface area, offer MORE braking capacity than any disc brake system could without multiple calipers. The big difference is in heat dissipation. Discs can withstand multiple hard applications due to their ability to shed heat quicker. A drum brake can't do that and it's that lack of ability to shed heat is what leads to brake fade.
But back to tires.... it's almost unbelievable that by 1970 tire technology was roughly the same as it had been since the advent of the tubeless tire (around 1948-1950). Sure, tread patterns had been played with and changed but the actual construction of tires had not. They were still the same old 4 ply, bias-belted, polyester or nylon-corded tires. About the only thing I can say in their defence is that them old Polyglas GT's just look SOOOO RIGHT on vintage cars. They are the epitome of cool. But their performance is garbage.
The big push for tire tech happened about that time as NASCAR teams were getting way up there in speeds and finding that tires of the day simply could not last on the super-speedways. Bobby Isaac's Charger Daytona topped 200 mph sure, but was finding that even the best race tires of the time would be shredded to pieces after 7 laps at that speed. What the tire companies learned on the super-speedways eventually trickled down to street cars and that's why you saw the big push for Radials around 1975.... and more cars being equipped with disc brakes around the same time.... radials can handle the higher braking forces of discs without losing traction.
Chrysler did have a rudimentary Anti-Lock system starting on the '71 Imperials but it was rear wheel only. I think Lincoln played with the technology as well. The systems did work, but the longevity of electrical systems back then wasn't the greatest. I recall reading a 1958 review of a Chrysler 300 equipped with the then cutting edge Bendix Electro-jector (the first Electronic Fuel Injection system) which did work and fairly well but was still really in the amoebic stage. The review goes on in detail how driving by a neon sign would make the car start bucking and acting weird until the sign got out of range. Chrysler designers had omitted an RF shield from the "brain" and stray radio frequencies could cause the car to act up.
Like Jay Leno says: "The last days of old technology are always better than the first days of new technology."
