Not sure I agree with the above. Textual Criticism, Etymology, and Scholarship in general isn’t an exact science. Hence, so many scholars disagree with each other. This doesn’t happen so much in actual science were we can verify any number of things. You can’t do that with history, so you must weight probabilities. Some give more weight to certain arguments over others.
That said, I do agree with your main point overall, I think. Meaning we certainly have more works to choose from via archaeology and hence broaden our scope further. The problem is, though, if we reduce your logic far enough, then we might assume the generation after Christ was inferior in knowledge in regards to the works and life of Christ, and the terms of that age than the 1500s, which was inferior knowledge to the 1870s, which is inferior to today. I think you can see that is false, and not very logical. The closer to the source, generally speaking, the more accurate. But with 2,000 years in between where books are burned, discarded, withered away, anything is possible. You could, in theory, have a scenario where we did know more in the 1500’s about than the 1900’s. It all depends on what works existed when, where and whether they exist today in the same form.
That said, you are likely more right than wring in regards to 1870s to today. However, people of that age we’re far more learned than we are today. Meaning each person was brilliant in comparison. The Harvards and Yales of that time were demanding and required a wealth of knowledge. They were more generalists. To be fair, though, a lot of that is due to specialization. Without it, we can’t advance much further. But with specialization, especially in a debatable topic, you end up maybe not quite a clear picture. Let’s say I am a specialist in one area of computers, because being a generalist is too difficult now. If I am good friends with a specialist in the “enterprise storage”, I’d be likely to take his word over many other specialists that exist in that field. Hence, I have’t really made up my mind in regards to the broader picture, I merely have my field of expertise and I adopted a viewpoint of a colleague on another issue without really knowing that is right. For science, specialization is brilliant. In theory all your specialists (or most) all come to the same conclusion. This is definitely NOT the case with scholarship specialization. You will have more dissenters, because, once again you cannot verify or prove much in that realm.
Language is so complex… Even today we have phrases (figures of speech) that don’t really mean what they mean! I am sure, relatively sure, that this has always been the case. I use them every day in life and love to point them out to my kids.