Portalblocks breaking by using water

Because Portalblocks are not a whole (outlined) block you are able to Focus on the blocks next to The Portal blocks. By using a water bucket on a block next to the Portal block, the portalblock will disappear and the water will be placed

 

The same workes with Dispensers, which are one block away and facing the Portal block. The Portal block will be removed too, like by using a bucket.

 

It might be useful for netherportal "Closing machines" but there is no other reason to "close" an end Portal that griefing