The only thing SE can do is leave the exp gain rate for losing but increase the mark gain for losing. That way even newbie players can at elast get their ilvl 70 easier to stand a chance, while also deterring Botters cause even with all those marks you'd still won't have enough rank for Ilvl 90s.
Why do you think that increasing marks would deter botters when they are currently doing it for less marks right now?

Again, take a look at WHY people are losing. The payout for losses is not the issue, the lopsided win/loss ratio for newbies and solo queue IS the issue. You are trying to place the bandaid on the wrong wound and will surely bleed out.