I could post a bunch of screenshots of Rebel Transports, Medical Frigates and other big Rebel ships heading toward Star Destroyers in the OT, but you get the idea.
The issue with that line of questioning is that the Rebels in the OT had quite a number of similarly-sized ships to the one Holdo uses, so even if you don't accept fighters going in hyperspace destroying Star Destroyers (which I do - Holdo's ramming produced damage far, far greater than a big ship ramming another big ship at speed, suggesting hyperspace itself enhances damage enormously, possibly regardless of ship size) there are many examples where they could have used it.
If the Rebellion throughout the OT was down to only one or two big ships like in TLJ, I could maybe accept the argument - but they aren't at all (the Resistance is down to a space-bicycle and space-jet-ski by the end of TLJ, so maybe we'll see who's right with the ramming in Ep IX.
)It all comes back to this lame "didn't think of that before..." idea - which given the high-stakes and desperation of the OT, is absolutely laughable and willful evasion.
for opening my eyes to what everyone kept secret from me for my entire life. 
