Amazon A Plus Content why ignored

So I myself have been selling on Amazon for quite a while now and I know a plus is something that we usually ignore. Recently I had my work done on fiverr from a guy, I just thought there is a space to place it so why not do it let’s do it and it did have an effect on the sales like I kid you not, I kinda thought it was going to be useless but it had like 10 to 20 percent effect sales and now seeing so many seller not having any A Plus Content just made me wonder like how many people are actually missing on this and why don’t people usually have their a plus content made and installed