I can't see anything in that explanation that would account for it being a fix for anything. I find the terms turn off and rise time confusing in the open collector context.
Equipment: Arduino Due, OP293A IR LED (2), PN2222A, 1K (2), 18R
Approx 100mA switched through the IR leds, powered by 5V.
No pullup
With 1K pullup
Switching time of PN2222A
A pullup helps a bit on the waveform shape for optical transmission, but what's even more important is the biasing circuit for the receiver (unknown/not posted).