A "systematic" change in the meaning of a word or phrase means that someone used it wrong once and enough people followed them in their wrongness that it became

A "systematic" change in the meaning of a word or phrase means that someone used it wrong once and enough people followed them in their wrongness that it became the norm. It's reasonable to say that once a new meaning has been taken up by the majority in this way it's not wrong anymore, but there is also a broad continuum between old usages and majority uptake of new usages where some users of the language in question may reasonably object to the latter. For instance, I was once CC'd on an email thread at work where a senior leader made an obvious typo in reference to some Thing and everybody else on the thread blindly parroted it. This "alternate" usage was established and used systematically in the local context, but it led to a significant decline in general clarity and interpretability, and it was also not durable beyond the context of that thread. It was a mistake, simple as that. "Comprised of" is probably past the threshold at this point, much like "rate of speed" and "how <thing> looks like" and so on and so forth. But—and I know this is shocking to some people—"correct" use of language does have significant advantages for communicating clearly, especially in writing. Prescriptivism and descriptivism both have their adherents because neither is right or wrong in the naive absolutist sense—balance is key.