Some of them are necessary for the functioning of the site, but you can decide about others.
Some time ago, there were rumors about a feature that could be used to generate high-definition (HD) heads for Vanilla Minecraft.
Normally, skin files only allow for an 8x8x8 pixel layout for the head, which limits the level of detail that can be achieved. However, with HD heads, there would be no such limit, allowing for much more detailed designs.
The concept involved uploading an image to the image folders of the education edition, which had no size limit, unlike regular skins.
As only images from URLs on Mojang servers are allowed to be displayed on the head, this technique allowed for the generation of such URLs, resulting in the creation of HD heads.
However, Mojang clarified that this was not an intended feature and patched out the functionality, leaving us with the hope for a future feature that would allow us to generate HD heads once again. ;-)