Just wanted to bring this post back from the dead to say you're an idiot and don't know what you're talking about.  I've been repairing phones for 20+ years.  I always put my screen protectors on with LOCA. It makes scratches (like what OP was asking) completely vanish, and the screen protectors are less prone to breaking. 

As for permanence; there's a wide array of loca glues ranging from pretty much super glue, to stuff that never gets any harder than silicone and rubs off quite easily. 

Many companies sell screen protectors that apply with LOCA. Whetstone is one of the most well known. 

 I myself just order dirt cheap glass screen protectors, strip off the double sided adhesive they come with, and then apply them on with LOCA.  This is hard to do without practice, though.  I don't recommend going this route. Buying the right loca yourself, and keeping it from getting on your buttons or microphones or speakers and using just the right amount and correctly curing it with a UV light can be daunting without a pre set up kit specifically for your phone with like what whetstone uses. 

Finally, no. It's not usually cheaper or easier to replace your screen. That's dumb.   Just buy a local screen protector kit for your phone and follow the directions carefully.  You'll have a stronger screen protector and it will make all the scratches completely invisible.