There has been significant advancement in speaker technology. Loudspeaker designers such as Alon Wolf of Magico use complex computer analysis and design tools to create a speaker with lower distortion and a more cohesive sound. This is accomplished with high-tech manufacturing tools capable of very fine tolerances, creating extremely inert /vibration-free, dense cabinet structures and exotic materials for drivers. Not to say that carbon fiber, graphene, beryllium, and sealed enclosure vs ported is always better as that is not the case.
I love JBLs, but 70’s and earlier models such as the 4350s, while sounding incredibly dynamic and loud, are significantly colored by the standards of current state of the art. The 4350 for example cannot be described as sounding balanced and ‘of a piece’ compared to some of the best modern speakers. They are also challenging to drive to sound their best. To these ears, JBL’s larger ‘paper’ bass drivers are still some of the best sounding bass drivers available. Compression drivers and horns done right will project a large, dense, dynamic sound. Many modern designs struggle with this and need high powered amplifiers to really come alive.