I'll go along with OhAlfie. I've had plenty of phones (eight?) in the past 20 years, plus I have the experience of my wife's phones and kid's phones (now grown up.) The only time I put a screen protector on a phone was my Pixel 2XL. My wife never has installed one and only one of my kid's did so. Never had a problem with scratches or pitting on any of our unprotected phone's screens. More recently, I did not put a screen protector on my 5a or my wife's 6a.
I put the IQShield Screen Protector on my 2XL. It was fine for about 3-4 months, but it did develop a small flap on the corner that slightly peeled away from the screen. Bugged me. Ironically I did get some small "scratches" in the screen protector itself even though I treated my 2XL the same way I treated all my phones. The neat thing about the IQShield was that I could "iron out" the scratches in the screen protector by applying some heat via a blow dryer.