Not so. There are those that believe objectivism is the true way of viewing the world. They view that we are on the way to understanding the universe as it truly is, that human perception will not pose an obstacle to that pursuit, and that there will eventually be one true method of viewing the universe in its entirety that is yet to be discovered. Constructivist beliefs directly oppose that idea, since all science is a man-made construct that can only approximate reality in their view. Constructivism also, then, leaves room for multiple theories coexisting because they provide better utility and insights in different circumstances. In the example of Einstein's Relativity vs Newton's Physics, we are talking about an older theory and the theory which usurped it because it was more accurate, and the general expectation is that another theory will be accepted down the line which will be better than both. That expectation is fairly objectivist, since it assumes there is a true model which we just haven't discovered yet. Constructivism does not make that assumption, since the universe likely does not fit neatly into our constructions in its image.

The other thing, is that constructivism challenges scientific realism to some extent, in that it challenges the existence of many things which we cannot directly observe, such as quarks, proteins, particles, etc... because "how can we actually confirm these things exist, when we physically can't observe them, and the things we're using to show their existence are constructs made up by us?"

This topic is still very much in a state of debate that has very strong implications around the philosophy of how science works and how it should be conducted. That's also just talking about constructivism's implications in the physical sciences. Things get much hairier when you start looking at the social sciences, where biases and perception are extremely influential on what we discover. Constructivism directly challenges the attainability of scientific objectivity, which has serious implications across all fields of science.