Your argument is irrelevant considering many things.
MK is so cheap and broken that many ppl play him. Therefore, he's just too freakin' common, and eventually ppl are going to know how MK plays, and will last longer against them, and as far I see it, the logic follows as:
"The more a person faces different ppl that use the same character with different styles, the more he/she will know how to play against the character.."
MK, being ridiculously popular due to being overpowered and being Sakurai's little demon pet, he's just a common sight. Ppl are going to catch on soon enough, whether they fight good MKs or bad ones. Though it's always better to try fighting good MKs, fighting bad ones has it's benefits, like what kind of spam you might go against and you slowly learn your way around it.
As we fight many different MKs, we try to find some ways that we can counter some of his rotton moves. This actually goes for against any character.
For us Pit players, we still got:
-Mirror Shield against many of MK's recovery options,
-Our great Piviot grab that Can grab MK out of tornado with right timing,
-Ledgecamping of course, though Metagay will either spamnado or rush in towards us.
-Our arrows.... It dont matter if Metagay can use the Nado as a shield, the fact that we have a projectile benefits us.
-Grab release to Dash attack takes good timing for best effect, but is an average way to kill, should MK get to about 145% due to DI, as I have tried on a lv 9 MK.
It doesnt matter if MK can gimp Pit, because ANYONE can, Metagay may do it better than some, but I even think Pit gimps Pit better than Metagay.
MK is still light, and this helps Pit, too, and not many ppl are realizing the obvious.
The problem being is that ppl are going to know how to live longer, or in some cases, slowly overcome Metagay as long as he's popular. This would make lower tier chars seemingly harder to fight due to them being rare to find. Pit being down on that biased tier list may actually help some Pit players as long as the opponents already dont have good experience against him, and I'm not talking about just fighting the spammers that plague this game like MK does.
To get better, one must generally fight spammers to know what kind of spam is out there to counter it, then fight good players of that character to know what potential and tricks those characters have to be aware of them.
That goes back to MK, which i mentioned before is already common. Besides, MK may actually be afraid to do some moves just because of what Mirror Shield can do.
Now I dont know what else to say atm, and I still say that Pit is disadvantages at 40-60 to Metagay. To me, G&W is even worse to Pit than MK is to him. And it isnt always about how well you can gimp opponents, but they do play a good role in matchups.