And because most readers are centuries removed form the original context of the text, a direct reading also skews their interpretation significantly because most will read it through their own 21st century lens (this is how chronological bias seeps in).
Companion texts (or commentaries) might seem like crutches or training wheels because they only present one interpretive option (which could reflect a commentary author's biases).
The remedy is use more than one commentary, not necessarily to discard all commentaries. Critical thinkers do this instinctively anyway -- for instance, we click on multiple Google News links to figure out what's going on.
Commentaries help a modern reader to get to speed on the historical context and thinking that was present during that era, which in turn helps them to formulate their own (more informed) thoughts. One could try to piece together this material by inferring stuff from the text, but chances are one would be wrong about the details and one would have to consult secondary or tertiary materials anyway.
In Chaim Potok's "The Chosen" (fiction), there's a Hasidic character named Danny Saunders who was a prodigy, praised by all for his intelligence. He had an eidetic memory and great ability for analysis, but found himself stumped when reading original texts in psychology. He studies German in order to read Freud, but he gets stuck on the fact German words can be understood in many different ways, when he only wants to find the ONE way.
He has a breakthrough when he realizes that Freud's works need to be studied, not read. His epiphany led to him studying Freud using Talmudic methods (with multiple commentaries), arguing with it, etc. and finally, the text yields to him.
TLDR: when a text stumps you, try reading it with multiple commentaries.