As everyone know, "hurt" isn't the same as "injury"--so why try to make such a point?
Again, Defenders have needed no such "inside info" to slow down Diggs, so his decline has proven your premise false. Also, "body slamming" a player to "take him out of a game" is an option on any tackle. If it really had that result with any frequency, and for such a low cost (15 yarder), logic dictates that you would see guys taking the penalty on an opposing WR1 more frequently. But you don't. So that's another dumb argument that gets endlessly repeated here.