My theory is that, just like with omitting a final comma in a list when not essential for meaning, publishers are trying to save paper and ink or pixels on-screen.

Champions behave like champions before they are champions

On occasion I omit commas. On occasion, I use them. (The more you know about English, the less you're likely to think there are unbreakable "rules" for a lot of these things.)

I caution against beginning or ending a quotation with ellipses

Nothing is more effective than sincere, accurate praise.

We all know gifs are pronounced "jifs," right? Their creator says so, damn it!

Concentrate on what will produce results rather than on the results, the process rather than the prize.