Paragraph Writing

I have a question concerning paragraph writing: When I started college back in the late 90s, in my English class we used a textbook that was first published in the late 80s-at the time we were using the latest edition- and did not mention anything related to concluding sentences as an essential part of paragraph writing. We only concentrated on the four bases of effective paragraph writing: Unity, Support, Coherence, and Sentence Skills. The only time when we focused on conclusion was when we transitioned from paragraph writing to essay writing, and we needed to produce a concluding paragraph at the end of the essay. However, nowadays, there seems to be a push for a concluding sentence (CS) for paragraph writing as early as in middle school.

Is it absolutely necessary to have a concluding sentence at the end of a paragraph?

I know that my question may appear silly, but I would like to know what more experienced writers have to say on this matter. I am a bit confused because when I was in high school and college we did not write concluding sentences (CS) at the end of paragraphs.

I would appreciate your feedback.