I might have agreed with that until yesterday. I was driving home in the early evening and came round a bend in a single-track road on a 1 in 10 hill, to have the very low sun shine straight into my eyes. I came to a halt as I could literally see nothing in the lane ahead with its high banks, because of the sudden extreme contrast. I had actually to stick my head out of the window as I edged forward since visibility was improved without the windscreen.Honestly, I hold the opinion that if other road users lack the awareness, or have such poor eyesight that they cannot see other traffic in daylight, let alone at night, they should not be driving/riding/walking/flying/sailing in the first place.
Had a cyclist been there as I stopped, there is no way that I could have seen them. Fortunately there was no other road user of any variety, and after a few yards I was in a shadier stretch and had no problems for the rest of the journey.
But it was quite a salutary experience (and I have been driving for 50 years and my vision is perfect apart from for close reading).