Smartphones and tablet are quite expensive especially flagship phone. No one wouldn’t want to spend a fortune and end up with a scratched screen. Many people still buy screen protectors and some even buy tempered glass screen protectors. In my POV, they have become less necessary.
Screen protectors were once practically mandatory, but advances in glass and coatings have made them unnecessary for most people. You don’t have to buy a screen protector (or even tempered glass) when you get a new phone.
To further elaborate on this, now most of the smartphones currently use Corning’s Gorilla Glass. This is a toughened, hard glass with high scratch resistance. Corning has actually been releasing new versions of Gorilla Glass over the years and each year it was up to 40% more scratch resistance than previous version.
Your smartphone’s screen is already fairly scratch resistant. That is if you have a recent smartphone and not one that is five years old. My old phone which is the Samsung Galaxy S7 Edge has been “naked” screen (without screen protector) until now still have flawless screen as you can refer to the below picture.
Screen protectors aren’t nearly as important as they used to be. They add a bit of extra protection to your phone, but that additional protection isn’t always necessary. Think of it like wearing knee pads while riding a bike. They’re super ugly, but they might come in handy during a freak accident.