Disagreement is not ignorance. The fact that a Linguistics 101 book contains a politically motivated viewpoint is unsurprising. That viewpoint is not factual.

Disagreement is not ignorance. The fact that a Linguistics 101 book contains a politically motivated viewpoint is unsurprising. That viewpoint is not factual. I have a relative who drops the R. He was raised around people (family and city) without that error, so clearly it didn't come about due to accent or dialect. Well, he invented his own, which is what a speech problem is. He was thus taken to speech therapy. Sadly the problem was not easy to fix. The speech therapist told his mother to not worry too much, because he sounded like he came from Boston. It does impact communication ability. Nearly everybody can clearly understand the speech of the national news anchors, particularly those of the 1970s and 1980s. Just the other day I met somebody with a thick native Florida accent, and communication was impeded. This matters. Getting back to reading, the more your speech differs from simple phonetics the more trouble you will have. Typical Russians learn to read a year or two before typical English speakers, and typical English speakers learn to read a year or two before typical Chinese speakers. If your speech is far from phonetic, your situation is closer to Chinese. That delays reading.