For a lot of people, "taking calls" is a major part of their job. I usually work remotely but, when I am in the office, hunting for a free enclave every time I need to have a phone conversation isn't practical and certainly doesn't scale if everyone were to do it.

I do think that it's on management to try to segregate groups that don't talk much and prefer quiet from groups whose jobs involve a lot of phone conversations but it's not practical for many roles to avoid talking on their desk phone. That's why they have one.