Its not difficult
How do you prevent players from "holding"?
You institute a penalty that is significant enough to mitigate - - - - at least to the degree that the league (the competition committee, or whomever) feel they have achieved the proper balance.
If the penalty was increased - say from 10 yards to 20 yards - what, do you think, would happen?
How do you prevent players from "roughing the QB"?
You institute a penalty for doing so.
If that penalty was reduced from 15 yards to 5 yards... what do you think would happen?
The NFL tries to reduce the number of infractions for DBs interfering with eligible receivers.... How? By instituting a penalty for such infractions (up to and including "spot of the foul").
If - like in college football - they reduced the maximum penalty.... lets say, in this case, to a "5 yard" penalty, what would happen?
RIGHT NOW, there is a penalty imposed when a player requires a stoppage in play and medical attention.
The penalty? We all know what it is..... player must leave the playing field for at least one play.
What, prey tell, do you think the league could do to reduce the number of illegitimate "injuries" requiring a stoppage in play.... if that is the goal?
(And that, obviously, is the goal as presented by the OP..... folks can "debate" anything they want, but THAT was the stated issue at hand)
They already have a rule in the books...... it is as easy as falling off a log to adjust the "penalty" (up or down) to either further reduce the number of incidents, or to loosen up play.
In this case, of course, the topic of the day is how to REDUCE the number of "questionable" incidents.
How would one do that? In an abundantly simple manner?
Is this somehow difficult? [Spoiler: It's not]