Different situations that are not comparable.
In one Luffy is using his entire force to pull Kaido back for an instant, by using special characteristics of his fruit, in the other Robin is completely subduing an enemy combatant to the extent of him not being able to do anything whatsoever.
So yes, it´s a measure of strength. Obviously it does not translate fully from requiring the exact physical strength of the opponent to do it, like you said, technique is also important, but the techniques without a certain amount of strength would not work.
And Robin pre-TS already had the capabilities of keeping Oars´arm in check, and he might very well be the physically strongest speciman in OP yet, the least one of the strongest.
In one Luffy is using his entire force to pull Kaido back for an instant, by using special characteristics of his fruit, in the other Robin is completely subduing an enemy combatant to the extent of him not being able to do anything whatsoever.
So yes, it´s a measure of strength. Obviously it does not translate fully from requiring the exact physical strength of the opponent to do it, like you said, technique is also important, but the techniques without a certain amount of strength would not work.
And Robin pre-TS already had the capabilities of keeping Oars´arm in check, and he might very well be the physically strongest speciman in OP yet, the least one of the strongest.

As I said Robin's physical strenght is nothing special, but she has great mastery of her devil fruit and submission techniques