OMISSIONS or ADDITIONS?: Why Are Thousands of Variant Readings Missing from the Modern Bible Translations?

WHY IS IT THAT OMISSIONS AS OPPOSED TO ADDITIONS SEEM TO DISTINGUISH THE WH NU TEXTS FROM THE TEXTUS RECEPTUS (RECEIVED TEXT)?

Why is it that we have what the KJVOists & TROists call omissions in the Wescott & Hort 1881 Greek New Testament (WH) and the Nestle-Aland 28th edition Greek New Testament (NA), 99.5% same), which the WH NA would argue are actually additions to the original texts.

Alexandrian Text-Type of Greek New Testament Manuscripts

The Alexandrian text … is usually considered to be the best text and the most faithful in preserving the original. Characteristics of the Alexandrian text are brevity and austerity. That is, it is generally shorter than the text of other forms, and it does not exhibit the degree of grammatical and stylistic polishing that is characteristic of the Byzantine type of text (Bruce M. Metzger)