Changes in materials and manufacturing processes happen all the time. That can come with issues. Just as "hand fitting" came with issues in the past.
If you need a part that has very high manufacturing tolerances you will pay more for it than the same part with more acceptable tolerance.
Costs are the driving factor. The Remington 700 and the 870 owned the general market. They did that by keeping the cost reasonable for an above average quality product for the average hunter or shooter. Can they do that again? We shall see.
Functionality is on the gun, accuracy is generally on the shooter. Can you buy accuracy? No. If you can't shoot a $800 rifle accurately, you probably can't shoot a $5K rifle accurately.
Everyone here will always argue which rifle or shotgun is better, same as they do in the caliber wars. Like anything, you won't hear a lot from the people shooting and having no issues. You will hear from the ones that do have issues.
I think more than quality issues, the absolute decline of customer support has hurt all manufacturers. For example, Smith & Wesson was the gold standard for customer support. They aren't anymore. But when you are selling more guns than you can get in people's hands; I guess they don't feel that is a big issue.
I started machining in 1971, I've seen a lot, some good and some bad. I will say this, you can pick any manufactured product you like, and we (manufacturing today) can absolutely outperform the same product and quality of the "old" days. But will everyone want to pay the increased cost of that product caused by more accurate machines, or highly trained machinists instead of machine operators. Some will and some won't. That's why many have varying product lines.
I hope our American gun manufacturers can hold the line and stay in business. Politics could end foreign imports.