So you're saying that later on even when you have weapons, there are stealth sections where you can't use them and immediately fail the mission if seen? We are talking about 'forced' stealth so just making sure that's what you mean. If so, that's terrible game design.
I'm not sure about that. The stealth sections seem to come in several different varieties.
One is the pure, no-weapon "forced stealth" you describe - no weapons available, and you fail if detected. I just completed one of those in Ch. 7. I had to sneak through a villa and take a compromising photo of someone. It was a short interlude in a larger mission. It took about 3 minutes; it was very easy. Those segments are rare. There may have been one earlier in the game, but I can't be sure. Lack of weapons made sense in context - you wouldn't want to hurt anyone in the situation.
The second type is stealth sections where you have one weapon available - a knife - but no guns. It's "forced stealth" in the sense that if you are detected, you fail. But you do have access to one weapon, so I'm not sure whether you would consider it "forced stealth" by your definition. The knife allows quicker behind-the-back takedowns (vs. choking), and some knives can be thrown from a distance, so it's part of stealth. It also allows you to crack into lockboxes you find along the way. I remember one of those sequences in the previous chapter, and I believe there were a couple of them earlier in the game.
The third type would be when I'm asked to infiltrate a camp or a compound. I'm instructed to sneak in and try to avoid detection, but I have weapons. Inevitably, I am detected at some point. Then the shooting begins. That would not be "forced stealth" but rather "stealth until you can't stealth no mo." These are somewhat common and usually involve extended encounters.
As others have said, all of the stealth in this game is easy. I don't think I've been caught once, and I'm not exactly Solid Snake. I would be the first to complain if the stealth was frustrating or the "trial-and-error" variety, but it isn't like that. You just sneak up behind some dumb guards, throttle them, throw them in a handy nearby crate, and keep moving. Occasionally you use bottles and such to distract them. It's pretty basic and easy.