I feel like I want to do a Pokemon analogy here
We all have our preferences in Pokemon. Some people enjoy the tough looking ones like Aggron while others might prefer the cute looking ones like Butterfree. Despite your preferences, these Pokemon all have their own stats: Attack, Defense, Special Attack, Special Defense and Speed. At the end of the day, some Pokemon are simply stronger than the others.
Suddenly, an expansion is released a few years post the official release of one of the major game's where you can compete with others online (I believe nothing like this has been done on a Pokemon game but for the analogy, Nintendo decided they would release an expansion for some extra moolah). The minor additions includes an increase in the level cap by 5 and adds a x1.1 XP boost. All this could be obtained for a simple 20$ (credit card only)
A few days after the release, two trainers decide to battle. One owns the new expansion while the other one does not. Let's call these two trainers EXPY (expansion:yes) and EXPN (expansion: no) for practical reasons.
Just because EXPY has a distinct advantage doesn't necessarily result in instant wins. Could be EXPN has the right types of Pokemon. Could be EXPY had the brilliant idea throws out a level 105 Metapod (Not even a Metapod which evolved from a Caterpie thus not having Tackle or String Shot) Maybe, despite having an XP bonus, did not sufficiently train his Pokemon enough when compared to EXPN.
Now in the event that EXPY wins a battle where both trainers have Pokemon of similar levels, we can never know if he won because of his advantages or not. Now of course a win is a win; it will be counted to his W-L ratio. EXPY won the battle legitimately by the game rules but hidden behind his ratio lies the uncertainty whether he won the games due to his advantage or skill.
Now this what I think on the issue of PC vs iDevice sparring. Since it is obvious that small advantages are found in in PC sparring (strafing and keyboard layout), how could a PC player find pride in his W-L ratio when he/she plays with a handicap in every spar matches. Problem with this handicap is that it does not even attempt to level the players strengths.