It’s been stated in other places on the forum in another post but the biggest reason for this friction comes from the fact that the antiseptic used to clean the skin will remove all oil from the surface of your skin. This leaves your skin about as smooth and frictionless as 80 grit sandpaper. But like worse. Basically your skin becomes like gecko feet and will stick to everything… So much so, that it actually feels tacky to the touch like it’s covered in adhesive. When you try to slide a steel needle through this, you’re doing so at such an angle that the length of the needle is often situated so that it must be dragged across the entire surface area of the needle making contact with your skin. That’s generating a lot of friction. Need a lubricant will make things go much easier.
The other issue is the bevel itself. The tip of a needle is made up of many parts, the point being the very sharp pointy bit… hence it’s called the point. The bevel, specifically the back part of the tube that gets cut into a needle shape… that does not have a cutting edge. So, when you are pushing the point through your skin, if you have not used the bevel down technique, then the needle bevel acts like a big scoop. The point slips under the skin, the edges cut the skin, and that makes the hollow center of the needle collect the skin inside it as it slides under. Once the back of the bevel hits the area of skin the needle is trying to slide under, you have a giant flap of skin sitting inside the needle now. Since the back of the bevel is not a cutting edge, it’s not going to cut that slap of skin, it’s going to require you to force the needle forward and effectively flip that flap 180° so it ends up sliding under your skin along with the needle.
Anyway the combination of these two things make certain installations very difficult. You can make it easier by using the bevel down technique, but once the back of the bevel is under the skin it’s recommended the needle be rotated 180° so the bevel is facing up while under the skin. This makes it easier to navigate the point the needle so that it’s not in danger of rupturing back out from under the skin so easily.