I appreciate their attempt with 1999 mode but people are going to find ways to break it easily. You can't turn a power fantasy sandbox game into a serious, balanced, and difficult action game by restricting reloads and buffing enemy stats. Western devs have typically been miles behind in hardcore skill based gameplay.
It's like Xcom's impossible mode. Sure you buffed the crap out of enemy stats, but the best way to play the game is still turtling behind hard cover with broken squadsight snipers. The other side of difficulty is balance and depth utilization (aka variety).