It is, if I may say so. Frightengly so. It might seriously hamper browsing experience, since it is so easy to put thousands of items or devs on ignore in a short time.
Though there are several mechanism to change behaviour. Simplest is to change the style from not show to show, but with a style that tells you, you probably do not want this item or already know it.
I can also stack styles. The screen is some fooling around with it. The page currently has 17 items that are modyfied. They all got blur style on top. The white stuff has opacity near 0. Upper right has a red outline. Lower right have scale half, for fun.
I do not know how to capture the essence of what happens, when I activate the style to be display none, since, well, the items are just no longer there, so there is nothing to show ;-)
