I believe that science evolved from natural philosophy. Does the "just" in the thread-title reflect a status-differential between philosophy and science that is the product of relative funding levels? After all, if philosophy was regarded as having greater value than science, wouldn't the thread ask, "is philosophy just a precursor of science?" Imo, it is better to think of philosophy and science purely as approaches to knowledge instead of as competing academic specialties. That way it becomes possible to compare scientific aspects of philosophy with philosophical aspects of science in terms of the two approaches as overlapping with differences in emphasis. The scientific approach tends to emphasize an object-orientation to observables, whereas philosophy tends to emphasize the capacity and logic of knowing and theorizing anything, including physically observable phenomena. Nevertheless, science cannot be rigorous without an ultimate concern for theoretical and methodological issues that are must be "philosophized" critically.So even though, in general, science is a much more important and useful subject to general philosophy, it is a branch of it nevertheless, due to definitions.
A "scientist" without oversight of the philosophical bases of their science is, imo, a technician working in the shadow of real science. This doesn't mean that such work is not as difficult, complex, or thought-intensive as more active theory-negotiation. It just means that a person who measures, records data, and processes the data without being on top of the theoretical/methodological philosophies underpinning their work is shirking total scientific rigor. On the other hand, isn't it possible to produce data that support or contradict a theory without understanding exactly why or how it does? Likewise, isn't it possible to know a theory without going beyond the level of accepting it for what it is and regarding it as something outside one's sphere of influence/critique?