It's because it felt like Jack did most of the work, and that he defeats Yuri at the end, rather than John.
shareJohn was just kind of in the way. Everything would have most likely been less of a mess without his involvement
shareNever understood the criticism that John made things worse for Jack. If John hadn't showed up at the courthouse and pursued Alik, they would've caught up to Jack, as we saw, and ended up killing him. It's hard to say if John hadn't intervened whether or not Jack would've made it to the extraction site with Yuri.
SPOILERS
But it could be assumed that Yuri would've found some way to escape from Jack or kill him before ever reaching the pickup location. Jack has no idea until the end that everything was an elaborate farce set up by Yuri to gain access to his vault of uranium, so essentially John's involvement is what stopped Yuri from succeeding. Alik was the only thing standing in his way. It looked to me like a lot of Alik's men were on Yuri's side all along. Both Alik and Jack would've died in due time if John hadn't shown up.