Higher level does not necessarily mean more modern language features and paradigm - it only means language's computation model is farther removed from the actual hardware.
Allen was specifically discussing auto-optimizations (what we nowadays would just call 'compiler optimizations') and essentially argued that low level languages, in the quest of allowing fine-grained manual optimization, prevent many types of advanced auto-optimizations.
Specifically speaking, it is well known that FORTRAN still often beats C in numerical calculations just by the virtue of not supporting pointer aliasing (especially pointers pointing to arbitrary positions in the middle of an array which is being looped over).
Allen was specifically discussing auto-optimizations (what we nowadays would just call 'compiler optimizations') and essentially argued that low level languages, in the quest of allowing fine-grained manual optimization, prevent many types of advanced auto-optimizations.
Specifically speaking, it is well known that FORTRAN still often beats C in numerical calculations just by the virtue of not supporting pointer aliasing (especially pointers pointing to arbitrary positions in the middle of an array which is being looped over).