The Punisher next to superheroes and villains... no thanks. He doesn't belong in that type of world where characters wear tight brightly color leather cat-suits. The Punisher is not a super solider, nor should he be shown as one. There would be no real reason for him to even be there, Frank Castle is just a normal person with no super powers or abilities, he's not super fast or strong, nor does he have incredible eye where he can shoot everything he sees. Sorry, but he wouldn't be able to bring or provided anything to a team in a MCU. You could just easily replace him with a nameless agent or soldier and not much would be loss.
One of the main reasons why Dirty Laundry worked so well is because it's set in the real world fighting real bad guys with real victims and with adult level violence. Thrown in spandex superheroes and villains with superpowers with a PG-13 rating... and it goes down hill.
Garth Ennis: "It's hard, it would be hard to do a story a story like the one I did with Nick Fury and have Spider-Man show up in the middle of it, it would instantly destroy the story, it just remove all creditable."