Ward cap and sight stones

So I noticed the past few games as support, I didn't buy sight stone. I typically don't rush ss in my elo unless bottom is getting focused hard by other lanes/roamers/jungle until after I start roaming myself. Maybe I'm just bad (quite possible), but more than likely I have noticed, like most of the randoms I've played with the past season or two, that you just get by with the ward trinket and come to depend on it entirely. All things equal, if everyone, including the enemy is limited in warding and only dropping 2 wards at a time, the game isn't impacted terribly much.

Of course this is arguable, and there will be those that maintain that warding > everything (and yes, I used to be that guy that stocked 5 stacks of greens back in the day, so I appreciate the power of vision). I guess the point I'm trying to make is, that in today's lol, being able to drop 3 instead of 2, and being able to B, restock and essentially pull up stakes and drop wards on the go, while definitely useful, isn't mandatory. I'm not even sure anymore that it is advantageous enough to tie up the slot where a potentially more useful support item could be.

My question is, since there are no more green wards, why should there be a ward cap? It makes perfect sense and balance to allow a max of 4 wards dropped with blue SS and 5 with red (I mean, if you are going to take up an item and spend 1600 just on a ward back pack, why not?) Everyone can still contribute to warding and have the same constraints, but supports that invest and commit to warding can actually feel that their purchase and contribution was rewarding (pun intended).