Why Grammar Matters: A Place To Discuss Matters Of Grammar

[shapeshifter]

1 hour ago, Milburn Stone said:

…the use of "So" to begin the answer to any question has become something of a universal tic…

I recall opening a very old (early-to-mid 20th century?) book in the college library where I worked for 19 years, and seeing several paragraphs beginning with "Now,…". My ex-husband's father, born at the end of the 19th century, was in the habit of beginning a sentence with "Now." 
"So" (which I frequently use) seems to have taken the place of the unnecessary "Now." 

1 hour ago, Milburn Stone said:

…the word "Therefore" would be a more formal way to start, but I feel like "So" and "Therefore" and "Thus" have become true synonyms in that context.

Now that I've re-read 👆this bit, I feel a bit better about the use of So and even Now. They do cue the reader (or listener) that the following words are a conclusion of what went before.

8 minutes ago, ABay said:

the writer could, and should, have left out So and started with It.

However, note that the "Now" at the beginning of my sentence above could not be removed without rewriting the sentence. At least mentally deleting "So" at the start of a sentence to determine if it's necessary is probably a good practice.

In the 90s I worked for 4 years at a college prep high school. The popular use of the sentence starter "So…" was peaking among the teen students. Students regularly recited a prayer over the intercom at the start of the day. After one of these recitations, our principal, the wonderfully feminist Sister Helen, wryly remarked: “I've never heard a prayer begin with 'So, in the name of' before.”
Sister Helen's remark has echoed in my mind for decades.

 

[EtheltoTillie]

I notice that "So . . . " is usually used in informal speech.  Not in formal writing. 

[fastiller]

In Ireland the word "now" is sometimes a full sentence (and not as a reply to "when?").  Generally when someone puts a cup of tea & a plate of biscuits (or a glass of beer or whisky) in front of you. 

[Milburn Stone]

23 hours ago, ABay said:

the writer could, and should, have left out So and started with It.

Having now read the material that immediately precedes the paragraph, I agree with you.