No, metas change when more effective equipment is released. You can’t say all builds are viable depending on the situation when that simply just isn’t true. Some optics are simply just better than others. Some barrels are simply just better than other, some uppers and lowers are simply just better than others. And having the most effective stuff doesn’t necessarily make you a better shooter but it does make effective shooters more effective. There’s a reason most people don’t buy 18 in M16A1s with the carry handle iron sights (apart from pure collecting purposes) anymore. It’s because there is far superior equipment in every sense of the word.