Short daily predictions organised by birth month are the most widely read form of astrological writing. The format is recent, and its conventions come from the requirements of newspaper publishing.
The format was built for a mass readership
Editors wanted a feature that every reader could find themselves in without supplying any information, and birth month is the only astrological input a reader knows without being asked.
That constraint reduces a chart with many variables to a single one, which practitioners of the older tradition generally regard as a severe simplification.
The commercial logic was strong, however, since a feature addressing all readers with twelve short paragraphs is cheap to produce and reliably read.
Each entry addresses a twelfth of everyone
A column entry is written for millions of people whose circumstances have nothing in common beyond an approximate birth period.
Statements specific enough to be wrong for most of them would fail immediately, so the writing gravitates towards descriptions that many situations can satisfy.
This is a constraint of the format rather than a fault of any particular writer, and columnists themselves have often said so plainly.
General statements feel personal for known reasons
People asked to rate a generic personality description written to fit almost anyone typically judge it as accurate about themselves specifically.
The effect is robust and has been demonstrated repeatedly in psychology courses, and it operates whether or not the reader believes in the source.
Readers also supply their own material, matching a vague statement to a specific event from their week, which makes the fit feel considerably closer than the text warrants.
The tone is prescribed by the setting
Columns are read casually and are expected to be encouraging, so entries tend towards mild advice and forward-looking framing.
Serious difficulty is rarely predicted, partly because it would be irresponsible in an unsolicited mass-market context and partly because readers would stop reading.
The resulting register, warm and non-specific, has become the popular image of the whole subject, which practitioners of chart-based work frequently object to.
The columns are not what the tradition does
Traditional practice works from a full chart requiring date, time and place, and interprets relationships between many factors rather than one.
Practitioners generally treat sun-sign columns as entertainment and distinguish them sharply from consultation, and some decline to write them.
Understanding the columns as a press format explains both their reach and why the wider tradition is uneasy about being represented by them.