Yes, paragraphs have a function. I should use them more often. I usually do. There is of coarse, no set limit to the number of sentences a paragraph should contain.
If there is one idea, and one point, they should be in one paragraph. Sometimes there are a lot of different ideas that are too small to separate into paragraphs.
At such times such as those, it can make for long paragraphs which are daunting to read.
I'm writing about my lack of use of paragraphs, and how I could have utilised them earlier for more effective posting.