It bothers me we cant get a clean 100% chance crit

All crit chance items: .

All the items that give raw crit chance also give attack speed and moviment speed. All the raw crit items give 30% crit. Why cant we get an Ad crit item that gives 20%? That'd make Ad crit item+ Atk speed crit item + Infinity edge a clean 100%. Would it be too of a buff to crit adcs? If its too much of a buff having 100% at 3 items, maybe the ad crit item wouldnt give that much Ad. If it gives 30 ad, i'd say it wouldnt defenitly be broken. So theoretically, we can bring that number up until its in the right spot?