opening up controller

Why doesnt playstation want you to open up a controller i wanted to open my contoller so i could clean the body with water because i like to play with a clean controller and after twoo year of playing with the same controller i thouht why not so i decided to take it apart i thouht this would be simple because i already took my ps3 controller apart once but when i tried to open my ps4 controller i ended up damaging it with a knife because i just couldnt get it open super frustrating normaly you shoold be abnle to just open it with your hand but i had to use a knife piercing it open and ended up scratching it when it got it open i saw twoo platic thing that kept the twoo sides thogether but broke of because i opend it ofcorse then i ask myself why the F do they secure it so much common it mine i should be abble to do with the controller what i want so why dont they want you to open it super irritating and fruatrating and stupid that i had to damage my controller just to open. Thanks
playstation....
(sorry for the bad english btw im from belgium)