We can't know why TI put the same value than in absolute maximum also to the recommended range.
The original National LM386 datasheet only lists the absolute maximum, and there is no recommended range listed at all. Multiple other manufacturers follow this as well.
On the other hand, it is still correct to state that it is recommended to be within absolute maximum range. So as long as you are within +/- 0.4V it is fine and it will work.
On the other hand, it might give a false impression that it is recommended to always use the full range, and that there is no downsides of using the full range.
In practice, the full input range can almost never be used, because the internal gain is at least 20 and the output must be within the limits of supply voltage, as only some LM386 versions accept supply voltage above 16V.
And of course, sound quality can suffer when going too close to the maximum input range, but sound quality may not be the top priority anyway when using LM386.
So for a robust design, you know your supply voltage and chip gain, and so the input voltage must be anyway limited so the output won't clip.